Tsukihi Araragi is a fictional character from the Monogatari series, created by Nisio Isin. She is the younger sister of Koyomi Araragi and is known for her fiery personality and distinctive appearance, which includes long, dark hair and a penchant for wearing a distinctive red dress. Tsukihi is a key character in the series, often involved in supernatural events and conflicts. In the story, Tsukihi is revealed to be a phoenix, which grants her unique abilities and immortality. Her character explores themes of family, identity, and the supernatural, contributing to the overall narrative of the Monogatari series.