早乙女 与一

Yoichi is a member of the Japanese Imperial Demon Army as well as Shinoa Hiiragi's squad in the Moon Demon Company. Before her death, his sister forced Yoichi to hide under their bed in order to survive and was then killed by Lacus Welt, while Yoichi was overcome by fear and watched this event happen in front of his eyes.

Like his sister, he was one of the children that was being experimented on by the Hyakuya Sect to create a weapon of mass destruction, as part of the "Seraph of the End" plan in destroying the world. 

Yoichi has an equilibrium of kindness and altruism, giving him an optimistic and sweet personality. This gives him a strong mental balance against his demon. However, he lacks strength and hates conflict. He wants neither his friends nor his family to die, but he doesn't want to kill anyone. Although he lacks the passion to exterminate vampires, he will do what it takes to protect his friends. He tends to be meek and stutters when he is most nervous. He is the peace-maker of the group and often tries to break up fights between Kimizuki, Yuuichirou, and/or Mitsuba.

He feels guilty for his sister's death, but this motivation is not strong enough for him to overcome his demon. His true strength and motivation comes from wanting to protect his friends and new-found family.

From url=http://owarinoseraph.wikia.com/wiki/Yoichi_SaotomeOwari no Seraph Wiki