Warning: This article contains spoilers for Higurashi, Kai, Gou & Sotsu. In the anime Higurashi and its sequel Higurashi: Kai most of the mysteries are resolved by the end of the story, but this question is one that the series never fully answers: Why does Mion Sonozaki carry a gun? Throughout Higurashi, Mion Sonozaki is shown to be the most powerful and capable member of Hinamizawa’s afterschool club. Her power manifests in many ways. She has an abundance of empathy, and she is in tune with what her classmates need and how they are feeling.
She has a great amount of political power as she is made the leader of most organizations she is a part of. She is also usually the one negotiating to save or help the lives of her friends whenever they have to deal with the heads of the three great families (e.g. Sonozaki, Furude, Kimiyoshi). When the club or village is in a state of conflict, Mion is the main one laying out the strategy and countermeasures for everyone else to follow. Her military expertise comes in especially handy when Miyo Takano and her counter-intelligence unit, the Yamainu, try to assassinate Rika and allow Hinamizawa syndrome to overtake the village. Mion’s ability to out maneuver the Yamainu is so effective that the Yamainu’s leader, Okonagi, admits defeat and claims that Mion has enough skill to join the SAS (Great Britain’s Special Air Service) or Delta Force (a special forces unit within the United States.)
The Sonozaki Family
Mion was selected as the next head of the Sonozaki Family, which would mean she knew how to use firearms. The Sonozaki Family is the most influential of the three great houses at the time Higurashi takes place. The Sonozaki Family’s role in the village is similar to the Yakuza, in other words, they are an underground syndicate that often operates outside of the law. There are many members of the family, and each of them knows how to use violence in order to accomplish their various ends.
During the events of the final fragment of Higurashi, Kasai (a bodyguard in the Sonozaki family) and Mion’s twin sister Shion both stay behind with guns to fight off the Yamainu. When Keiichi expresses concern for Shion’s safety, she reassures him by saying it would take less time for him to run than it would for her to teach him how to use the gun she was holding. Her words seem to reveal that she has been trained in the use of firearms, and as Shion is Mion’s twin, and the two have received nearly identical training, that Mion would know how to use firearms as well.
Due to her exposure to the people and the operations of the Sonozaki family, it is highly unlikely that Mion was untrained in the use of firearms. In fact, the most plausible reason for Mion to be carrying a gun is explained by her role as the next head of the Sonozaki family. She might either need protection from assassins or a weapon to carry out the various underground operations of the family. Though both of these reasons are plausible, Mion is never shown on screen engaging in Sonozaki family operations, She is never shown to be defending herself from assassins, and she is never shown to be using her gun.
The Gun Was Never Used
Mion never once uses her pistol on screen, even though there are situations where using a pistol would help resolve a conflict or help her out of a bad situation. Towards the end of the series, after the club has finally succeeded in thwarting the operations of the Yamainu, Okanagi leaves Takano a gun with a single bullet in it. He leaves her the one bullet so she can take her own life, but instead she uses that bullet to try for one last attempt at Rika’s life. Takano takes aim, but before she can pull the trigger, Mion steps in front of Rika with her arms outstretched. The moment is touching, yes. Mion demonstrates that a true leader is willing to sacrifice anything for the wellbeing of their companions.
Mion would not have had to sacrifice herself or anyone else if only she used her gun. With her gun nobody would have to die. All she would need to do is draw her weapon and fire it at Takano. She could have nuetralized Takano in many ways, by disarming her, or shooting at a non-vital organ. Mion had the skills to shoot with accuracy, and she was just a few feet from Takano. There are many other places in Higurashi where it would make logical sense for Mion to use her gun either to protect herself, or help those around her. Mion could have used the gun to defend herself from Shion, to protect herself from Keiichi when he was overcome with violent paranoia, or even to fight against the heavily armed Yamainu.
There are No Answers
Higurashi never gives any clear answers as to why Mion has a gun and why she never uses it. Perhaps Higurashi would not have been as good of a story if Mion used the gun. It's possible that her gun was just part of the character design that the artists thought looked cool. The mystery has caused some theorizers to speculate as to if the gun was real. The gun could have just been a modified airsoft gun. However, these theories are just that, theories, and unfortunately, fans of Higurashi are going to be forever wondering what Mion was doing with a gun.