Mion Sonozaki

Mion Sonozaki (園崎 魅音) is a member of the Sonozaki family and leader of the club. Mion is the heir to the Sonozaki family and acts as Oryou Sonozaki's right hand. As the family heir, Mion is well respected among the villagers of Hinamizawa.

Background
The name "Mion" along with the headship of the Sonozaki family was reserved for the first-born of the Sonozaki sisters. Because of this, Mion was born as "Shion Sonozaki" as she was born second. Furthermore, her sister Shion was originally named "Mion Sonozaki". As the firstborn, Shion was made to attend family meetings to prepare for the headship. Mion found this unfair and proposed that the twins occasionally swap names so that both could attend family meetings. However, the twins swapped names on the day that the first-born was to be branded with an oni (鬼) tattoo. As a result, Mion was permanently, and falsely, branded as the firstborn heiress to the Sonozaki family. She permanently adopted the name "Mion" while her sister adopted the name "Shion". No one other than the twins appears to be aware of this fact.

During her upbringing, Mion became an expert in martial arts, with enough skill to defeat Okonogi in hand-to-hand combat.

Mion is the oldest student in the Hinamizawa school and acting class president. She also acts as leader of the club organizes most of the games that the club members play.

Appearance
Mion appears as a pretty young girl with green hair, often tied into a ponytail. She bears a tattoo of a demon on her lower back. At school she wears a white shirt, beige vest, a red tie and a long red skirt. Her casual clothing consists of blue jeans, a short-sleeved yellow t-shirt, and a white sweater tied around her waist. For athletics she wears a typical Japanese PE outfit with blue bloomers and a white t-shirt. In her Steam sprite, Mion's PE shirt sleeves are rolled up. For swimming, Mion wears the old-type Japanese school swimsuit. In her Steam sprite, Mion instead wears the new-type Japanese school swimsuit. In the, Mion wears a Chinese-style two-piece red-and-yellow bathing suit. Despite her exposed skin, Mion's tattoo is not visible on her back while wearing this swimsuit. This is because Mion owns waterproof skin makeup reserved for such outfits.

In her original sprite, Mion carries around a airsoft gun in a holster on her left shoulder.

When working at Angel Mort, Mion wears a costume containing a mix of several fetish outfits. She wears a seifuku top with bloomer bottoms along with a cat tail and bell.

Personality
Mion is very cheerful and energetic. She enjoys games quite a bit, especially those she plays with her fellow club members. She is particularly adept at the games the club plays due to Mion's proficiency at cheating. Because of her skill, Mion has won the most games out of all the club members, though Rena Ryuuguu reveals that Mion was initially the worst of all at the club games. Mion frequently acts tomboyish often calls herself "oji-san", (translated as "Uncle Mion" by MangaGamer). Her tomboyish personality sometimes causes problems with her relationships, most evidenced by Keiichi Maebara's mistaken belief that Mion wouldn't like "girly" things such as a stuffed doll he won in a contest. This mistaken belief actually fuels the escalated Hinamizawa Syndrome in Shion Sonozaki and leads to the events of. However, Keiichi manages to subvert this future in by giving Mion the doll, which she accepts and cherishes.

When acting as heir to the Sonozaki family, Mion remains extremely formal and responsible, in stark contrast to her usual personality. She becomes very serious and almost completely expressionless. This is most evident in, wherein Mion forces Shion to rip off three of her own fingernails despite Mion's love for her.

Despite her somewhat "wild" personality, Mion remains the only main character of who doesn't commit murder or become dangerously violent.

Hinamizawa Bus Stop
Mion is one of only two Higurashi no Naku Koro ni characters to appear in the non-canon Hinamizawa Bus Stop. Mion is younger and more timid than she is in her canon appearance. Mion is chosen, against her will, by the Ministry of Health and Welfare to be the new host of the "parent insect" inside Rika Furude.

Onikakushi-hen
Mion serves as a major antagonist in Onikakushi-hen and ends up being bludgeoned to death along with Rena Ryuuguu by Keiichi Maebara.

Watanagashi-hen
Mion serves as the primary antagonist of Watanagashi-hen and successfully kills Rika Furude, Kiichirou Kimiyoshi, and Oryou Sonozaki and ultimately dies by falling down a well. She frequently disguises herself as Shion, leading to confusion as to how Keiichi ends up stabbed and how Shion dies. Assuming the events of this arc resemble, Shion is the true antagonist of this arc, stealing Mion's identity and murdering her friends.

Tatarigoroshi-hen
Mion appears as a relatively minor character in Tatarigoroshi-hen and frequently serves as a source of information for Keiichi Maebara about Satoshi Houjou. Mion becomes hysterical for a short while when Keiichi asks her to take Satoko Houjou to the Watanagashi Festival, the same request that Satoshi had made of her a year prior.

Himatsubushi-hen
Mion appears only once in Himatsubushi-hen, as a mediator for Oryou Sonozaki during a flashback to a village meeting.

Meakashi-hen
Mion plays a major role in Meakashi-hen as the twin sister of the main antagonist. Mion ends up a victim of her sister's psychosis and is locked in a cage and made to watch as Shion kills of Mion's friends throughout the story. Mion ends up being murdered by and having her name tarnished by her sister.

Trivia

 * The "on' in Mion's name is written with the character "音" meaning "sound". The same character is in Shion's name as well as every servant who worked at the Fukuin House such as Shannon and Kanon.
 * Mion's long red skirt that she wears to school is reminiscent of a Japanese sukeban, a reference to Mion's status as a yakuza heiress.