Chapter 21 (Quartet Knights)

Plan (計画) is the 21st chapter of Tashiro Yumiya's Black Clover Side-Story: Quartet Knights.

Summary
Noelle comments about how Luck is pretty hurt and asks why he always have to get into nasty things. Luck says that he wants to stop the enemy, and informs Noelle that the stone tablet within the Sand Dungeon is still intact. Luck then asks if he can still fight, which Noelle tells him that he can't. Noelle tells Luck that Asta is ready to fight and that they will be taking over the fight.

Vetto and Asta start to clash. Vetto comments that Asta was at the Lava Dungeon and wonders if he came here to die, which Asta replies that he has come to save Luck. Asta attacks, which Vetto dodges and goes to counterattack. Noelle blocks the attack with her Sea Dragon's Nest spell, which Vetto comments about how that was cunning. Vetto says that the spell was childish and attack but finds that the Asta is no longer in the spell. Suddenly Asta appears behind Vetto and manages to wound him. As Asta thinks about how he was able to wound Vetto, Luck warns him that Vetto doesn't feel pain. Vetto attacks but Asta is able to dodge it. Vetto comments about how Asta's rapid movement is annoying and attacks, but Asta manages to block it. Asta thinks about how Vetto's power is amazing and that he can't stop it. Asta is sent flying, which Noelle manages to catch him with her magic. Asta notices what Noelle did for him and thanks her.

Noelle then asks Luck about what he means about Vetto not feeling pain, which Luck explains how Vetto continued to attack even through he had cut Vetto's arm off. Luck also says that Vetto had reattached him arm, which Noelle comments about how Vetto was able to do that at the Seabed Temple. Luck says that this is different since Vetto was not using his Grimoire and that this is something different then normal magic. Noelle wonders what Luck means, but remembers that Karna has create a copy of Vetto from his mana and that his body might be made of his mana. Noelle thinks about how this explains everything since a copy would only move using its instincts during battle. Noelle also thinks about how broken the magic is and that they have not choice but to do this. Vetto comments about how he has had more fun then he thought, but it not enough since he needs more overwhelming despair. Vetto comments about how Asta said that he had come to save his friend, then charges at Noelle and Luck while wonders what would happen if Asta would lose his friends. As Asta, Noelle, and Luck are shocked by this, Vetto comments that Asta would feel a huge amount of despair. Asta also charges, while Noelle prepares a spell. Vetto says that they are slow and attacks, but Yami suddenly appears and blocks the attack. As Asta, Noelle, Luck, and Vetto are shocked by this, Yami asks if they wait too long.