Arc 2

The Dungeon Exploration Arc (探索編) is the 2nd arc of Yūki Tabata's Black Clover.

The arc revolves around the exploration of a newly emerged dungeon at the border of the Clover and Diamond Kingdoms.

Reunion
One day, a peasant who is walking in a forest suddenly encounters a ruin of building that had emerged from the ground. A few hours later, Yami Sukehiro approaches several members of the Black Bull squad who are hanging out and informs them about an emergence of a dungeon. Hearing the news, all of the members become excited before Asta shows his ignorance regarding the existence of dungeons. The other members then start explaining to him that a dungeon is a place that contains a hefty amount of treasure, including powerful magic items, but also is guarded by countless powerful traps.

Vanessa Enoteca then adds that due to the danger of powerful magical artifacts landing in the wrong hands, it is the duty of the Magic Knights to conquer the dungeon and secure the treasures. Yami then further explains that the dungeon emerged on the border between the Clover Kingdom and a neighboring country, the Diamond Kingdom.

After hearing all of the information, Asta quickly nominates himself for the mission. To everyone surprise, Yami reveals that the Wizard King himself has requested for Asta to explore the dungeon. Asta then immediately travels to the dungeon along with two squadmates, Noelle Silva and Luck Voltia. On their way to the inner-side of the dungeon, Asta and Noelle start arguing about the name of the anti-bird that they met during their mission at Sosshi village. After several name proposals, they decide to use Luck's suggestion of naming the bird Nero.

Back at the Black Bull headquarters, Vanessa is curious about the Emperor's awareness of Asta but Yami simply says that their leader is weird. Additionally, the Black Bull's captain also assures her that Luck Voltia should be able to protect the new members. Although, he also remarks on Luck's slightly insane personality.

After a brief walk in the dark, due to Asta accidentally dropping their source of light, the group finally reach the inner-side of the dungeon. Luck and Noelle immediately remark the dungeon to be full of mana. Asta begins sulking due to his inability to sense or have mana. However, during his tantrum, Asta suddenly activates a trap spell. After he easily neutralizes it, Luck suddenly pushes him into another trap. Additionally, Luck begins to activate several other traps before stopping and praising Asta's Anti Magic weapon.

Luck then begins sensing the presence of others inside the dungeon and quickly heads out towards the strongest person that he sensed, leaving the new members on their own. A moment later, another plant-based trap spell suddenly entangles Noelle but Asta manages to release her. However, the spell is able to strangle Asta as well before preparing to eat him. Suddenly, a rain of swords falls upon Asta and destroys the trap.

During that time, at the Black Bull headquarters, Yami informs Magna Swing that several members of the Golden Dawn were also tasked to conquer the dungeon. Back at the dungeon, when Asta and Noelle look up, they see the appearance of the members of the strongest squad, one of which is Yuno.

Back at the Golden Dawn headquarters, William Vangeance is interrupted by Alecdora Sandler, who inquires into the captain's decision to assign the dungeon exploring mission to Yuno. However, William only asks Alecdora to trust his decision. Returning to the dungeon, the Black Bull members and the Golden Dawn members are facing each other with Asta and Yuno delighted to be reunited. Unfortunately, Yuno's senior, Klaus Lunettes, interrupts them and asks his junior the reason for his action of saving the Black Bull members. Klaus's remarks spark a confrontation between the nobleman and Asta.

Furthermore, Mimosa Vermillion also starts a conversation with Noelle, her cousin. While being passive-offensive, Mimosa begins to boast about her group's achievement of a star at their previous mission. Asta and Noelle then cheerfully reveal their achievement as well but Klaus brushes them off as lies.

Subsequently, Klaus also asks the Black Bull members about their missing third member, and both of them unable to give him an answer. Meanwhile, Luck is still cruising through the dungeon towards his target's location. When Klaus begins to mock the Black Bull squad, Asta challenges him to a race to see which squad can reach the center of the dungeon first. Accepting the challenge, Klaus orders Mimosa to scan the dungeon and Yuno to create a vessel for their transportation.

After the Golden Dawn members leave, Asta and Noelle also head towards the center. As they begin to encounter many creatures of the dungeon, Noelle questions their method of choosing the path as neither of them is able to find the correct path. Seeing the two of them struggling, Nero takes off from Asta's head and points them at one of the paths. At the same time, the Golden Dawn members are traversing the dungeon towards the center. When Klaus begins to belittle the Black Bull again, Yuno reminds him not to underestimate Asta.

In the meantime, at the Royal Capital, Julius receives a report that the Diamond Kingdom has sent a group of mages led by Lotus Whomalt to conquer the dungeon. While the rest of his attendants are panicking, the Emperor is still confident of his Knights' abilities.

Back at the dungeon, Luck finally arrives at his target's position. After defeating all of his subordinates, he challenges the leader to a fight while confirming that he is his target.

Clover vs. Diamond
After observing Luck's abilities, Lotus decides to escape while proposing for a nonviolent competition to conquer the dungeon. Unfortunately, his opponent refuses as Luck charges at him. Lotus is able to dodge the attack with his Smoke Magic while also revealing his standing with the Diamond Kingdom. He then tries to explain his reason for exploring the dungeon and his Kingdom's constant invasion to the Clover Kingdom, but Luck tells him that he just wants a good fight.

At the other side of the dungeon, Asta and Noelle are still trying to find the correct path to the center while struggling in an area with an abnormal gravity. Asta tries to ask Nero's guidance but the anti-bird remains silent. Asta then notices a walking treasure chest just pass them and immediately captures it. However, when they open it, they see the chest's internal organs, which annoys Noelle.

The fight between Luck and Lotus continues with the latter in the defensive side. While observing his opponent, Lotus recognizes the robe that Luck is wearing as the Black Bull signature robe. He then begins to reminisce his fight with Yami and tells Luck about his defeat from the Black Bull's captain. The story quickly excites Luck but he suddenly starts feeling hazy. Lotus then reveals that he has been casting a weakening spell since Luck's arrival as the boy loses control over his body.

The Golden Dawn members finally arrive at the center of the dungeon. As they are discussing it, Mimosa is suddenly ambushed. When Klaus demands the perpetrator to come out, Mars then reveals himself as he walks towards them and tells them to get out of his way.

Lotus then decides to leave but Luck quickly gets up and tries to attack Lotus again after hearing his mother urge him to win. The fight continues with Luck releasing even more magical power. The Black Bull member then begins to reminisce his childhood days while living with his mother. He remembers that his mother used to slap him for his constant smiles and his inability to show other emotions. However, when Luck managed to defeat a noble at his school, his mother began to praise him while urging him to keep achieving more victories.

At the same time, Luck begins to put pressure on Lotus as the man realizes that Luck is getting stronger even after he weakened him. Lotus then decides to end the fight as he restrains Luck within Smoke Binding Cross Prison.

At the center of the dungeon, Mimosa activates a Dream Healing Flower Basket and begins to heal herself. The Golden Dawn members then notice the diamond symbol on Mimosa's attacker and assume that he is from the Diamond Kingdom. A fight then ensues between Klaus and Yuno against Mars.

At the other side, Asta and Noelle finally find the correct path. However, when Asta hears an explosion and Noelle senses it to be Luck, Asta suggests that they head there and help Luck. Disagreeing, Noelle reminds him about their objective and Luck's own decision to leave them for his own agenda.

Returning to the center, the fight between the Golden Dawn members and Mars has reached a stalemate but Klaus realizes that they are being cornered as the fight drags even longer. He then orders Yuno to leave and conquer the dungeon by himself. Yuno tries to reason with him first but ultimately decides to leave. Seeing an opening for an attack, Mars binds one of Klaus's feet and launches an attack towards him. At the same time, after binding Luck with his spell, Lotus decides to put Luck out of his misery by trying to suffocate him.

Fortunately, Asta manages to arrive in time to destroy Lotus's binding while Yuno decides to turn his back and saves Klaus from Mars's attack. When Klaus questions his decision, it reminds Yuno of another vow he made with Asta where they would treasure their comrades like they care for each others. Additionally, when Lotus asks about Asta's relation to Luck, he reveals that he is Luck's friend, which is a similar answer to what Yuno gives Klaus when he asks him about his main priority on the mission.

Sadly, after remembering her mother's funeral and the promise he made to keep winning, Luck declines Asta and Noelle's help. He then charges towards Lotus but the latter yet again evades him and tries to launch a counterattack. Asta immediately interferes while reminding Luck that they are comrades. Hearing it, Luck has a change of mind and agrees to defeat Lotus as a team. However, Lotus also decides to stop fooling around and traps all three of them inside a veil of thick smoke.

Meanwhile, Yuno finally releases the full extent of his magical capabilities. Klaus is taken by surprise when he realizes that Yuno has been keeping his strength a secret as the latter activates two spells concurrently.

The Black Bulls are still struggling to break out of the ever replenishing smoke that Lotus created. Luck then praises Lotus for his sensory abilities as the man is still able to evade all of Luck's attacks amidst hiding within the thick smoke. Not long after, Luck suddenly notices something and devises a plan to defeat Lotus. He then starts by sending a barrage of attacks towards the Diamond Kingdom's mage. As Lotus evades the attacks to the side, he is ambushed by Asta who suddenly appears from within the smoke. The boy swings his sword at Lotus and manages to inflict heavy damage to him.

Luck then reveals his plan where he needed to guide Lotus towards a certain direction while Noelle launched Asta towards the designated position. After their plan succeeds, Luck expresses his delight on the notion of teamwork.

On the other side, even with his full strength on display, Yuno is being suppressed by Mars who is finally using his grimoire in the fight. Looking back at his defeat, Lotus praises the Clover Kingdom for having someone without magical powers in their ranks while also deciding to escape along with his subordinates. After failing to capture Lotus, Luck suggests that they return to their original mission of conquering the dungeon. At the same time, he also senses someone with an even more powerful magical prowess than Lotus.

The fight at the center of the dungeon continues with Mars easily overpowers Yuno while Klaus is watching from afar. After observing for a while, Klaus notices the mage stones embedded on Mars's body and they remind him of a rumor that the Diamond Kingdom had performed an inhuman experiment towards their mages. Subsequently, seeing his uselessness in the fight, Klaus tries to launch an attack towards Mars. Unfortunately, Mars simply creates a crystal doll of himself, which is strong enough to keep Klaus occupied while he continues to attack Yuno.

Yuno tries to retaliate but his attacks are unable to penetrate Mars's defenses. Seeing his opponent's futile effort, Mars suggests Yuno to surrender. Mars's ultimatum reminds Yuno of his childhood days when he is training with Asta where he learns to never give in any situations. After refusing to give up several times, Mars is finally able to corner Yuno and about to deliver a devastating attack. At that moment, Asta steps in and saves his foster brother by destroying Mars's Laevateinn.

Asta then demands Yuno to give him an explanation for his pitiful state. Yuno tries to deny Asta's claim, which sparks an argument between them before they prepare to fight Mars together. When Klaus sees Asta is able to easily destroy Mars's spell, the nobleman becomes flooded with questions. Distracted, he does not realize that Mars's puppet is about to attack him. Luckily, Luck is able to step in and save him in time. Regrettably, the fact that he is saved by a Black Bull member is very embarrassing to him.

At the same, Noelle finds her cousin cooped up inside a magic spell trying to recuperate. She quickly casts a protection spell around Mimosa while promising to keep her safe. On the other side, the fight continues with Mars creating several other puppets of himself to attack all of the Clover Kingdom's mages.

He then focuses his attention on Asta who manages to easily destroy the puppet that was about to attack him while the others are handling the rest of the puppets. Mars tries to attack Asta with another Laevateinn, but Asta easily slices it apart. Additionally, Asta also manages to break every single attacks that Mars launched at him and sends him flying into the nearby pool.

Asta's feats once again confuses Klaus until Noelle explains to him that her squadmate is able to nullify magic. However, hearing Noelle's explanation only resulted in Klaus mocks Asta even further. On the other hand, Mars regains his standing and activates Heavy Armored Titan, which clads him in a moving armor of crystals. With the use of the said spell, Mars manages to inflict a significant damage but it is still not enough to put his opponent down. Seeing Asta's durability, Mars asks about his opponent's identity, to which Asta says that he is just a human without any magic power. Klaus is about to belittle him once again but the sight of Asta's highly developed muscles quickly silences him, especially after he hears Asta's ambition to become the Wizard King.

When Mars hears Asta's ambition, it reminds him of Fana and his forgotten duty to protect. Trying to brush the memories off, Mars tries to put an end to Asta but the latter's attack manages to render him unconscious. Upon Mars's defeat, all of his puppets also cease their movement and Asta declares that the dungeon's treasures belong to the Clover Kingdom.

The Sword
In order for Mars to attack the Clover Kingdom's mages even further, Klaus decides to put a restraining magic spell on him. However, when Asta questions the effectiveness of the spell, Klaus annoyingly mentions the former's previous challenge in which the Golden Dawn managed to reach the center of the dungeon first. Subsequently, they start arguing on a method to enter the dungeon's treasury. After sensing that the treasury's door is composed of magical power, Luck suggests that Asta forcefully cuts a path for them. Immediately after they enter the treasury, all of them are in amazement upon seeing the amount of treasures that are stored within it.

All of them begin to explore the treasury whilst trying several magic items that are hidden among the gold and jewelry. Seeing his squadmates' behavior, Klaus immediately reprimands them by saying that those items could be very precious. Yuno then notices that streams of wind are surrounding a peculiar scroll, which placed in the middle of a heap of treasures. He then opens the said scroll and finds a series of writings that he could not understand. Suddenly, the scroll and his grimoire start glowing and the writings vanish.

On the other side, Nero is trying to take Asta to see a wall by pulling his hair. the two of them then arrive in front of a wall with similar locking mechanism as the treasury's door. When Asta is unable to comprehend Nero's hint, the anti-bird starts pecking on his head yet again. At the same time, Luck senses a familiar magical power and immediately warns his squadmates. Unfortunately, he was too late as Mars storms into the treasury and binds Klaus, Yuno and Luck with his crystal magic.

Klaus then notices that Mars is able to recover by using a fire-based healing magic spell. The sight takes him by surprise as Mars's mana should have an affinity to crystal and a mage could only use magics from a single element. Klaus then postulates that Mars's ability to use magics of two different elements is the result of the Diamond Kingdom's experiment. At that moment, after storming into the treasury, Mars begins to remember another fragment of his memories where Fana is trying to attack him.

Not long after, he notices that Noelle is trying to douse his healing magic with her water magic. Mars quickly incapacitates Noelle and manages to inflict a critical damage on the Black Bull's mage. Seeing his injured squadmate, Asta quickly charges towards Mars but the latter reveals that he already has an understanding of Asta's fighting patterns as he launches a barrage of attacks.

The former is unable to withstand the said attack and is easily sent flying through the wall where he was standing beforehand. Unable to find a strategy to defeat Mars with his heavy sword, Asta sees Nero flying passed him and landing on top of an ominous sword. Seeing the sword that Nero has been hinting at, Asta quickly tries to reach it.

Outside of the hidden room, Mars continues to remember fragments of his memories during the experiment when he was talking to Fana about what they would like to do after completing the said experiment. One of Fana's wishes was to see the outside world alongside Mars. Unfortunately, the wish could never come true as the Diamond Kingdom's researchers revealed that only one of them could complete the experiment as the final test was a death match between all of the participants. Hearing the ugly truth, all of them began to kill each other and at the end, Fana ultimately tried to attack Mars as well. Mars ended up killing Fana and had several mage stones embedded on him while his grimoire was fused with Fana's grimoire, which enabled him to have more than one elemental affinity.

On the other end, Mimosa begins her healing process on Noelle's injury while reminiscing her childhood days playing with Noelle. As she grew older, Mimosa began to master various high level Healing Magic spells while Noelle remained unable to control her magic power. At the time, Mimosa was only able to watch as her family made fun of Noelle even though she witnessed her cousin training far harder and more tenacious than her. Those memories resulted in Mimosa's deep respect towards Noelle as she encourages her cousin to stay alive.

Mimosa's act catches Mars's attention and he decides to finish off both of them. Unfortunately, Klaus, Yuno, and Luck are unable to help them as they are still trapped within Mars's crystals. To everyone's surprise, Asta manages to intercept Mars's attack just in time to protect both of them. Asta then charges towards Mars while neutralizing all of the latter's attacks with his newfound lighter sword. However, Mars's healing magic spell is keeping Asta from landing any significant damage.

At that moment, Noelle finally wakes up and immediately tells Asta that he is the only peasant whom she acknowledges. She then orders Asta to quickly finish the fight. Asta's sword begins to glow and when he swings it to neutralize Mars's attacks, a flying slash of water comes out of it. This slash cuts through Mars's defenses and douses his healing spell.

The Wind
Unfortunately, a shard of Mars's Harpes pierces Asta's stomach. Seeing his opponent has fallen, Mars immediately goes in for the kill as he creates another giant sword. While Noelle and Mimosa are unable to move, Klaus and Luck are still struggling to break free from Mars's binding. Yuno is the only one who is able to break out of the binding. Although he deems that none of his spells are fast enough to save Asta from Mars's attack, he refuses to give up. Suddenly his surroundings become quiet as everything has stopped moving. At that moment, Yuno notices a little girl with a pair of wings at his side. She seems to have been just awakened from a deep slumber as she gives out a big yawn.

The little girl then blows a little gust of wind towards Mars who is about to kill Asta. Suddenly, everything starts moving again and Mars has received a devastating attack from Yuno's direction. The moment Klaus tries to find out about it, the crystals that have been binding him and Luck vanish into thin air. Seeing the phenomena, Klaus is convinced that Mars has been truly defeated.

When Yuno looks back to the little girl, she has already vanished and the writings that he found on the scroll are now inside his grimoire. Additionally, the sword that Asta found also starts shaking and enters Asta's grimoire. On its place, a series of writings is also appearing on the page of the said grimoire. At that moment, while Noelle requests Mimosa to attend to Asta's wound, the dungeon begins to crumble with the spots where the scroll and the sword were located as the breaking points.

The Dungeon has Fallen
As the dungeon is collapsing, Yuno quickly creates a vessel for them to escape. Immediately, Luck carries Asta to the said vessel and Mimosa starts her healing process. Although, she doubts that she could completely heal him with her remaining magical power. Before they take off, Asta requested that they bring Mars with them because their mission is not to kill their enemies. Unfortunately, the dungeon is already in such a critical state that they are desperately in need to escape, so they decide to leave Mars behind.

While steering the vessel, Yuno is unable to determine the best path to the exit and Mimosa, who was their guide beforehand, is occupied. They are fortunate enough that Luck is there to give Yuno guidance with his sensory skill. At the same time, Luck and Klaus are also working together to clear the path from falling rubble.

At the end, they manage to escape from the dungeon and Yuno quickly asks them to carry Asta to a safer place and continue his healing process. In that moment, Lotus finally shows himself again as he revealed that he was around during Mars's fight against the Clover Kingdom's mages, collecting the dungeon's treasures. Lotus and his subordinates are also able to escape by following the trail of the Clover Kingdom's mages after saving the unconscious Mars as well.

While he is unconscious, the last fragments of Mars's memories begin to resurface where he was grieving for killing his best friend. Suddenly, all of his wounds were healed as he realized that Fana was using her healing spell on him. The dying girl explained that she had to make the choice as she believes that Mars was the most suitable to complete the experiment. Before she dies, Fana requested that Mars explores the outside world for her share as well.

Subsequently, Mars wakes up with Lotus congratulates him for a job well done as they are able to secure a hefty amount of treasures. At that moment, Mars notices the panoramic view of the outside world as he remembers his promise to Fana. He then gives his gratitude to Lotus for saving his life. The sudden change in Mars's attitude slightly surprises Lotus as the latter remarks Mars's newfound personality.

Back at the outer-side of the dungeon, Asta finally opens his eyes. When Mimosa is mesmerized by Asta's vitality, Yuno believes that high vitality is his only virtue. Asta retaliates by saying that he will not die until he becomes the Wizard King, with which Yuno disagrees as the title is his for the taking.

While Asta is trying to stand up, Klaus suddenly approaches them and hugs Asta and Yuno. He then apologizes for his behavior during the mission while also acknowledging that they are an excellent Magic Knights. Unfortunately, Klaus's noble act does not receive a proper reception as they are being indifferent about it. Asta also remarks Klaus's side personality, which slightly annoys the nobleman. At that moment, Luck takes an advantage of the situation and requests a fight against Yuno but the latter quickly refuses Luck's approach. Noelle also slaps Asta when he highlights her shredded attire.

Fights

 * Luck Voltia vs. Lotus Whomalt
 * Klaus Lunettes and Yuno vs. Mars
 * Luck Voltia, Asta, and Noelle Silva vs. Lotus Whomalt
 * Asta vs. Mars

Events

 * Blood Brothers Reunion
 * Hidden Treasures: the Sword and the Wind