Although he was lonely and unwilling to leave his room at first, eventually he warmed to the cheerful red-haired girl Hisui who would come every day to ask him to play, and in turn lead his shy and often-nervous sister outside as well. Shiki lived in a small Japanese-style building on the grounds of the Tohno's western-style mansion for a time, learning to accept and be accepted by his new siblings. In a moment of amused irony, Makihisa spared and adopted the boy because his name was unisex with the name of Makihisa's eldest son, Shiki (四季, SHIKI ?). Shiki was the only survivor of that attack. The Nanaya clan lived in a secluded mansion in the mountains, but was one night destroyed by the Tohno and Kouma Kishima. It is revealed in Kagetsu Tohya that he is the son of Kiri Nanaya. While the Tohno family is a family with demon blood, Shiki's real surname is Nanaya, a family of powerful demon-slaying assassins. Shiki is in fact not a real member of the Tohno family, is not Akiha's biological brother, and is not Makihisa's son.
