A second-year high school student from Tokyo, a science-minded boy in the physics club.

Kenji Koiso

17 years old, a second-year student at Kuonji High School in Tokyo. A member of the physics club, he is a shy and introverted science-minded boy. He planned to spend his summer vacation working a part-time job maintaining the network with a friend, but by chance, he is invited by his crush and senior, Natsuki Shinohara, to visit Ueda City in Nagano Prefecture. He is gifted in mathematics but regrets failing the Japanese national team selection for the Math Olympiad. However, that talent eventually becomes the trump card for facing a global crisis.

A refreshing beauty in a white dress.

Natsuki Shinohara

18 years old, the eldest daughter of the Shinohara family. She is the great-granddaughter of Sakae Jinnouchi. A member of the kendo club and a school idol, she is Kenji's senior. She goes to Ueda City, Nagano, to celebrate the birthday of her great-grandmother, Sakae, during summer vacation. However, to fulfill a promise to Sakae to "bring a fiancé next time I visit," she asks Kenji Koiso to take on the part-time job of being her "fiancé." While she is a refreshing beauty in a white dress, she also has a bit of an airheaded side.

A world champion in combat net games.

Kazuma Ikezawa

13 years old, one of Sakae's great-grandchildren. He appears to be a gloomy otaku boy who stays shut in his room, but he is actually a world champion in combat net games and a master who controls "King Kazma" in the cyber world. He is a super player sponsored by global corporations. He is confident in his skills, and his attitude led to him being bullied in the past. To master fighting games, he continues his training under the guidance of his "Master."

The 16th head of the Jinnouchi family, which has continued for centuries since the Sengoku period.

Sakae Jinnouchi

The 16th head of the Jinnouchi family, which has lasted for hundreds of years since the Sengoku period. She is the matriarch of a large family spanning four generations, including great-grandchildren. Celebrating her 90th birthday, many relatives gather from all over for the occasion. A woman of great vitality who doesn't show her age, she is well-versed in traditional martial arts. Inheriting the spirit of her ancestors who served their homeland during the Sengoku period, she possesses a wide network of connections in politics and business. She accepts Kenji, the suddenly appearing "fiancé," and leads her clan to face the global crisis.

Mansuke Jinnouchi

70 years old, the second son of Sakae Jinnouchi. He runs a fishery business in Niigata Port. An active fisherman who takes his own boat out to sea, he is a physical powerhouse with master-level skills in Shorinji Kempo. He is the "Master" who taught Shorinji Kempo to his grandson, Kazuma Ikezawa, via OZ.

A wanderer, but the possessor of a genius-level sharp intellect.

Wabisuke Jinnouchi

41 years old, the illegitimate child of the late grandfather who was the previous head of the Jinnouchi family. He ran off with the family assets and was missing for ten years, but suddenly returned on Grandma Sakae's 90th birthday. It seems he was immersed in artificial intelligence research in America during that time. In fact, that is the root cause of the major incident and seems to be related to "Love Machine"... Though a wanderer, he possesses a genius-level sharp intellect. He is also Natsuki's first love.

Takashi Sakuma

17 years old, Kenji's classmate and fellow member of the Kuonji High School physics club. The physics club is commonly known as the "PC Club," and their part-time job is performing maintenance on OZ in the clubroom.