Tsukihi Araragi (阿良々木 月火, Araragi Tsukihi) is the younger sister of both Koyomi Araragi and Karen Araragi, and the youngest member of the Araragi family. She is the younger half of the Tsuganoki Second Junior High School's Fire Sisters. She is nicknamed Rara by her childhood friend Nadeko Sengoku and is the titular protagonist of two arcs: Tsukihi Phoenix and Tsukihi Undo.