Klaus Lunettes and Yuno vs. Mars

Klaus Lunette and Yuno vs. Mars is a fight that occurs during an exploration of a newly emerged dungeon.

Pre-fight
After cruising through the dungeon under Mimosa Vermilion's guidance, the Golden Dawn members finally arrive at front of the door to the treasury at the center of the dungeon. As they arrive, the three of them begin discussing on the method to unlock the door. Subsequently, Mimosa touches upon the whereabouts of the Black Bull members whom challenged them to see who could reach the center of the dungeon first.

At that moment, Mimosa is suddenly ambushed by a barrage of crystals that manage to break her defenses. As she falls to the ground, Klaus Lunette demands the perpetrator to reveal himself. The said man, Mars, then walks towards them as he orders them to clear a path for him.

Fight
After suffering a significant damage from Mars, Mimosa quickly activates one of her healing spells and begin the recuperation process. At that moment, Klaus shouts at Mars for his dirty act of launching a sneak attack at a female. However, Mars is unfazed as he then tries to finish the job by launching another attack at Mimosa but Klaus swiftly defends his squadmates.

A fight begins with both sides are able to block each others' attacks. However, when Klaus sees that Mars is able to effortlessly attack and defend from the combined efforts of him and Yuno without opening his grimoire, the nobleman knows that they are being pressured. He then orders Yuno to leave him behind and conquer the dungeon on his own. Yuno disagrees at first but quickly obeys his senior's decision.

During that time, Mars sees an opening and quickly binds one of Klaus' feet before launching an attack at him. Disregarding his order, Yuno comes back and protects Klaus from the attack. When Klaus reminds him about their priority on the mission, Yuno reveals to him that his priority is his comrades as the former releases his full strength and activates two spells concurrently.

To Klaus' surprise, Yuno with his full strength is still unable to fight Mars in equal ground against Mars whom is finally opening his grimoire. As he sees his junior struggling against Mars, Klaus is frustrated for his own uselessness and tries to launch an attack towards Mars. However, the latter simply creates a puppet in which strong enough to keep Klaus occupied.

Mars then continues his assaults on Yuno as the latter tries to retaliate. However, Yuno's efforts are unable to breakthrough Mars' defenses in which the latter demands the former to surrender. Yuno refuses to give up as he continues to evade Mars' every attack. The prodigy still refuses to give up even when Mars finally able to corner him and about to deliver a devastating attack. To everyone surprise, Asta steps in just at the right time and destroys Mars' spell.

Post-fight
After blocking Mars' attack, Asta remarks Yuno's losing state but the latter quickly brushes it off. After a brief arguments, Asta and Yuno prepare to fight against Mars together.

In the meantime, Klaus is distracted by Asta's appearance that he is unable to react against Mars' puppet that is about to attack him. The nobleman is saved by Luck Voltia whom manages to intercept just in time, but Luck's kind act put shame on Klaus as he realizes that he is being saved by a Black Bull member. On the other side, Noelle Silva finds her cousin laying helpless inside her spell. Noelle then immediately put a protective spell around Mimosa as she promises to protect the latter.