Mion Sonozaki

Though she is supposed to be the heir to a Yakuza family, Mion likes having fun and playing tricks on others in good faith. She loves playing games. She has a care free, tomboyish attitude about most things. She's very caring towards others. She is very attractive and has large breasts. She knows how to handle a firearm. Even though she is tomboyish, she has a feminine side that she wishes to express and to be seen, even if it does make her flustered. She's bad at lying about her true feelings.

Mion is the heir of the Sonozaki family and is the leader of the Hinamizawa School club. As the oldest in the class, she is the Class Representative. She is the granddaughter of Sonozaki Oryō, the current Sonozaki head. Because her mother, Sonozaki Akane, married a man from outside Hinamizawa against Oryō's wishes, Oryō passed her inheritance to Mion rather than Akane. Since the Sonozaki family is quite rich, Mion has a large allowance. The 50,000 yen announced as the winning prize at a game tournament is said to come from her own pocket. She is a tomboy, and since she is the oldest among the rest of the students, she refers to herself as "oji-san (叔父さん)" – "old man (literally "uncle" but used generically)" – throughout the games, manga, and anime, though she also has a girly side. It is very often strongly hinted and ultimately revealed that she has a crush on Maebara Keiichi, which she expresses by picking on and teasing him at every possible occasion as well as confessing her feelings to her twin sister. Due to being the oldest child and thus the heir, Mion was branded with the oni (鬼) – "ogre" or "demon" – tattoo presumably on her back. Her name also contains mi (魅), a kind of forest demon or elf.

Mion is actually the younger twin, and she was therefore born with the name Shion. Mion and Shion intentionally switched places when they were young because "Shion," the current Mion, felt it was unfair for only one of them to attend family meetings while the other had fun. They switched places the day the oni tattoo was to be applied, resulting in the younger sister, "Shion," the current Mion, becoming the next heir. No one but the twins themselves seemed to be aware of this.

Mion acts boyish, energetic, and confident, often teasing her friends. She is a very cheerful and sociable girl who enjoys games. As the leader of the after-school games club, she organizes various card or board games, which she has become extremely good at, partially through cheating. Mion designs most of the "punishment games" that the loser must perform, but, again, in the beginning, she often had to do them herself. It is a tribute to her determination that she has advanced so far in skill. Although Mion seems very self-confident and tomboyish, it is revealed that she is quite girly. As the heir to the Sonozaki family estate, she must act very formal and responsible when dealing with family matters. As a result, Mion has another side of her personality that contrasts with her normal self. When she assumes this role, she becomes almost completely expressionless and very serious. She is seen to be very straightforward and always goes directly to the topic, avoiding any other conversation that might interrupt.

Mion has long, mint green hair and turquoise eyes. Her bangs part in the middle, and she ties her hair into a ponytail with a yellow band. She has a trim figure and a large bust. She has a large demon tattoo on her back. Mion wears a white short-sleeved shirt with an amaranth red tie and wears a sunshine yellow, unbuttoned vest. She also wears a long magenta skirt, black socks, and chocolate brown shoes. Alternatively, she also wears a sunshine yellow shirt with a slight black turtle neck, a white sweatshirt tied around her waist, navy blue jeans and chocolate brown shoes. She also wears an airsoft gun in a holster on her shoulder.