Yuichiro is the main character of Seraph of the End. He want to kill all Vampires for enslaving humans and to avenge his adoptive family that was made from the orphans kids like himself.
Yuichiro was an orphan who's father tried to kill him and his mother spread rumors that he was the son of a demon and then killed herself. Yuichiro was sent to the Hyakuya Orphanage were he meat Mikaela who wanted to befriend and make him part of the orphanage "big family" despite Yuichiro not being interested with in it seeing that he have no family. However, despite this the other orphans greeted their "new brother Yuu" into the family. At the same moment a lethal l virus stared to kill all those who are above thirteen and the vampire announced their presence and enslaved the surviving children and kept them as livestock for blood. Yuu and the others were taken to the underground vampire city where they remind for four years.