Yūichirō Hyakuya 「百夜 優一郎, Hyakuya Yūichirō」is the main protagonist of the Owari no Seraph series. He is a member of the Japanese Imperial Demon Army and Shinoa Hīragi's squad in the Moon Demon Company. He, along with Mikaela Hyakuya, possesses the "Seraph" gene, which is relevant to the forbidden taboo and the focal point of the story, "Seraph of the End."