Seraph of the End 4: Guren Ichinose: Catastrophe at Sixteen

Seraph of the End: Guren Ichinose's Catastrophe at 16 (Volume 4) is the fourth volume of the Seraph of the End: Guren Ichinose's Catastrophe at 16 light novel series which includes Guren's past with Mahiru and his encounter with many characters of the manga sequel, Seraph of the End: Vampire Reign.

Prologue
Guren Ichinose contemplates what he should do while facing imminent failure: 1) give up, 2) keep trying anyway, or 3) fight to fulfill your ambitions and risk losing everything else. Guren chooses option three.  He is filled with desire and despair.  In a small alley, he risks his humanity and grasps the demon weapon Noya.  He senses the Apocalypse begin.

Chapter 1
Guren hears a voice calling his name and awakens in a completely white space in his heart. The demon Noya tempts him with power and approaches him. He chats about Mahiru and says that Guren will turn into a demon regardless of whether he accepts that power or not. Guren touches Noya and willingly gives up his humanity, leading Noya to mock him for making the wrong choice. He says it is unacceptable for a human to give up on his humanity while he is still human. Everything goes black, and power overwhelms him.

Guren wakes up with the sword in his and a motorcycle next to him. He hears war going on all around him but no longer feels any pity or empathy. His desires encourage him only to kill, and he mutters about needing a sheath to suppress the demon's will before getting onto the motorcycle.

Characters
List of characters in order of appearance: