The Demon's Nightmare is the twentieth chapter of the Seraph of the End: Vampire Reign manga series.
Shinoa's squad watches over Yu, and Shinoa explains that Yu is talking to his demon. The unconscious Yu begins shaking, and Kimizuki takes care of some nearby horsemen.
Yu meets with Asuramaru, who is high from his blood. Asuramaru explains that all vampires become demons in the end. He explains how to loosen the curse in order to gain more power with an increasing risk of Asuramaru taking over. They fight, and Asuramaru fills Yu with illusions of his Hyakuya orphanage family and his biological family. Yu regains control by thinking of Mika. Yu stops fighting and coaxes Asuramaru to join him. He says he will love him, and eventually Asuramaru gives in.
It has been longer than the anticipated 20 hours. Shinoa explains that he is talking with his demon inside of his heart. By establishing a bond, the human will loosen the curse constraining the demon and may access more of the demon's power. Yu's body suddenly starts shaking, indicating that he made a serious connection with his demon.
Horsemen arrive, and Kimizuki goes to intercept them. The remaining three soldiers guard Yu and hold him down.
Asuramaru giggles and gasps with delight at the taste of Yu's blood, causing Yu to calmly respond that Asuramaru is acting like a vampire. Asuramaru tells him that demons are the mere shadows of what used to be a vampire. He wants Yu to give him more of his blood, his body, his mind, everything. Asuramaru leaps at Yu, wanting him to give him his everything and let him ravish him. Chains start binding him, restraining his movements. Yu asks him about the chains holding Asuramaru prisoner and he explains to Yu that it's the sorcery that humans completed in order to curse the demons and bind them, and that they are trapped by it. Yu asks him if it's painful. Perplexed, Asuramaru denies any pain. He wonders why Yu would worry about him and Yu responds by saying that he dislikes painful things. Asuramaru agrees and calls Yu weird.
Yu goes back on topic and asks Asuramaru what he should do, as the only thing he was told was that if the demon sucked his blood, the Cursed Gear would advance. Asuramaru tells Yu that when he drinks blood, the demon curse's restraining force goes down. He says to move on even further, he needs to explain a variety of things to Yu. When Yu is confused by this, Asuramaru says that the explanation about this curse and the contract was something that the humans decided. If he doesn't tell Yu, he'll be stuck in the demon curse chains and won't be able to move. Yu asks if it's a manmade curse and Asuramaru confirms, telling him that human sure are scary because they keep putting their hands on forbidden techniques. He also says that the thing inside Yu is quite terrible as well. Yu does not remember losing control and Asuramaru laughs, stating that humans sure are despicable.
Disregarding it as something that has nothing to do with him, Asuramaru explains the rules to loosen the demon curse's binding force. Simply put, he will attack Yu and every time he takes one of those attacks, his willpower will go down. If Yu's willpower goes down, he'll be taken over. Yu finds it odd that it is essentially Asuramaru trying to take over him. Asuramaru tells him that its a demon's objective to and only reason why they listen to humans. Asuramaru then tells him that if Yu is able to cut him with the sword, his own willpower will go down, and that if Yu can "slice [him] into submission", it's game over and he wins.
He warns Yu that he won't even be able to touch the sword before he starts to break the chains. He tells Yu that because he explained the rules, the curse's restraining force weakened. Asuramaru is almost totally free of the chains and wants to start the fight so they'll see who the real master is. He keeps talking about the restrains weakening, and his reasoning is fading. He wants Yu's everything and then tells him to die. He then attacks Yu, knocking him back. He gets on top of him and teasingly asks him if he is in pain, but he says that he won't let Yu die. He reiterates that Yu will have a nightmare every time he takes one of his attacks and his spirit will be brought down. He wonders aloud how long Yu will last.
The illusion shows Mika calling Yu terrible for leaving him behind and Akane saying that it's the reason why Mika was turned into a vampire and that it's all his fault. Yu coughs up blood but breaks free, telling Asuramaru that he won't give in to something like that. Unabashed, Asuramaru says he will as the demon curse has gotten weaker and so he'll touch Yu's true darkness and let his rages and desires run wild. He then bites Yu, which shows him another illusion.
Yu appears as a child, when he was still at home with his parents. In a room with a tipped-over table on the floor with bottles, papers, pens, and drinks spilled, Yu faces his parents. His mother kneels on the ground in the kitchen with her back to him while his father curses him, calling him demon spawn. He says he must kill the Seraph of the End as soon as possible or else the world will be ruined. Yu notices his dad holding a large knife and tries pleads with him, saying that he'll be a good kid. His dad says that killing Yu is the right thing to do. Yu cries that he's not the devil and his dad chases Yu into a massive apartment hallway, where he sees Akane and Mika again. Mika says that because Yu ran away, he became a vampire. Akane wishes that Yu hadn't come to the orphanage since everything's gone horribly wrong since he came and that he should've just died here. Yu's dad appears in the doorway and tells him to die as this is the end for him. The illusion of his dad stabs Yu in his back through his left chest.
Yu says he will not go berserk over something like that. He talks about the promise he made to Mika as he was the first person to ever need him. He visualizes a kind 12-year-old Mika who says that they'll protect their family and that he'll be counting on him. When he asks Yu if he's alright, Yu responds that he's fine. He adds that because Mika wanted him that he'll definitely save him. Yu then wakes up with tears in his eyes.
Annoyed, Asuramaru thought that he had won and Yu says that he already knows how to fight. Yu summons the sword and Asuramaru compliments him but tells him not to kid himself. Noting that he must have gotten weaker, he even calls Yu a demon that wasn't wanted by anyone and discarded by his parents. Yu tells him that those kinds of words don't hurt him anymore and that he is fine with being a demon. He says that if Mika, Guren, Shinoa, Yoichi or Kimizuki need him, he doesn't care about something like that.
Asuramaru says that him being defiant kind of annoys him and Yu asks him what he's gonna do about it and Asuramaru tells him that he'll kill him. Yu throws away his sword, deciding against attacking Asuramaru. He says that if he did, Asuramaru would see a nightmare like he did and he does not hurt his friends, which makes Asuramaru laugh. He says that Yu is being naive, but Yu says that he doesn't care if Asuramaru is a demon as he needs him. Yu asks him to be his friend in order to save Mika and his family. In exchange, Yu says he will be Asuramaru's friend since Asuramaru must be awfully lonely. Asuramaru agrees to let Yu possess him and tells Yu to grab the sword. When he does, he feels the power flowing through him.
Yu wakes up, much to his team's relief.
Characters in Order of AppearanceEdit