|Kanji Name||幸一 逢沢|
|Age|| 9-10 (TNKitA)|
13 (TNKitA II)
|Birthday||February 20, 2023|
|Height|| 4'2"/128.0cm (TNKitA)|
4'9"/146.5cm (TNKitA II)
|Family|| Kakeru Aizawa (father)|
Nana Aizawa (mother)
Suguru Aizawa (uncle)†
Mito Aizawa (aunt)
Keiko Aizawa (older sister)
Ryo Aizawa (older sister)
Hiroki Aizawa (older brother)
Yusha Murasaki (younger half-brother)
Saito Shirayuki (brother-in-law)
Tamaki Shirayuki (nephew)
Sakae Kajikawa (wife)
Aoi Aizawa (son)
|School|| Kamakura ES (TNKitA)|
Kamakura MS (TNKitA II)
|Status|| -TNKitA: Elementary Schooler (4th grade), Player for Kamakura Wolves|
-TNKitA II: Middle schooler (2nd yr), Player for Kamakura middle boys team
|Hometown||Kamakura, Kanagawa, Kantō, Japan|
Koichi, like his sister, Keiko, resembles his father, but in miniature form, almost to the last detail.
Koichi is very attached to his older siblings. However, he's a very quiet child and far from being the most social in the house. Nevertheless, Koichi mainly makes friends with children of his age.
Koichi has an excellent sense of anticipation to cut passes and start the counterattack with a good first pass. Like his namesake, Koichi Hibino, the youngest of the Aizawa children has a powerful shot with his left foot, so much that even Hiroki has difficulty in making saves against this kind of shot.
- Kakeru: As Koichi's father, he has a close relation to him.
- Nana: As Koichi's mother, he is just as close to her as he is to Kakeru.
- Mito: Koichi and her siblings' aunt. She regularly visits them, as she lives close by.
- Keiko: Keiko is Koichi's oldest sister. He calls her Onee-chan.
- Hiroki: Hiroki is Koichi's older brother and Ryo's twin.
- Ryo: Ryo is Koichi's older sister and Hiroki's twin. He calls her Onee-Chan.
- Sakae Kajikawa: Sakae Kajikawa is Koichi's wife. She was originally Koichi's middle school homeroom teacher, but later got into a relationship with him, resulting in pregnancy, when Koichi grew distant from his family.
- Ohana: a girl, she's one of Koichi's friends in elementary school.
- Toru: a boy, he's one of two elementary school friends seen with Koichi.