Mion Sonozaki

Mion Sonozaki is one of the main characters of Higurashi no Naku Koro ni Kai, the twin sister of Shion Sonozaki, and the recognized heir to the Sonozaki family. She is the granddaughter of family head Oryou Sonozaki, who passed the inheritance to Mion after Mion's mother married a man from outside Hinamizawa against her wishes. At the village school she is the oldest student in her year, the class representative, and the leader of the after-school games club.

Boyish, loud, and endlessly self-assured, Mion often calls herself "oji-san" (roughly "old man"), even though she has a softer, more feminine side she rarely lets others see. She designs the club's games and the punishment forfeits for whoever loses, and thanks to her family's yakuza ties she is trained in both martial arts and firearms. Much of her energy in the story goes into teasing Keiichi Maebara, a habit that masks real feelings she eventually admits to.

Mion's defining secret is that she and her sister swapped identities as children: the twin born second took on the "Mion" name, the family's heir tattoo, and the burden of becoming the next head, while her older sister became "Shion" instead. No one outside the two of them knows, and they still trade places at family meetings without being caught.

Outside her family duties, Mion is a fiercely loyal friend to Rena Ryuuguu, Satoko Houjou, and Rika Furude, for whose safety she has repeatedly put herself on the line.