Momiji Hozuki (穂月 もみじ) is a cheerful and energetic character from Onii-chan wa Oshimai! She is Mahiro’s younger sister and plays an important role in the story as one of the people closest to him, often helping drive the comedy and everyday slice-of-life situations. Momiji is friendly, lively, and affectionate, and her interactions with Mahiro and the other characters add warmth and humor to the series. She helps highlight the family and social dynamics at the center of the story.