Tsutsumiuchi is an old man who appeared in a flashback in a timeline that occurred before Shunsuke Otosaka's interfence using his time leap. Tsutsumiuchi had worked with a group of scientists, that had a lot of power where they kidnapped children in order to study supernatural powers; one of the scientists' goal was to create a medicine that would strengthen the children's powers, making them harder to get rid of even if the children reach the age where their powers were to disappear. To achieve their goals, the scientists would do whatever they see fit which includes performing inhuman experiments, such as how they planned to dissect Ayumi Otosaka, to restraining or killing any children they deemed as too powerful. Tsutsumiuchi, disgusted with how his colleagues worked, waited for a chance to save the children using Yu's plunder to help Shunsuke to use his time leap.
Yu and Ayumi are listening to music. When they are finished, Yu notices the old man is there again. As he wants to pass by, the man suddenly says how much he likes classical music. Later he appears when the building is crushed and there's blood all over him.
Later, in the new timeline, Tsutsumiuchi appears working with Shunsuke Otosaka where he is now developing a vaccine that would prevent people, from getting powers, once comet Charlotte arrives again.
The old man is in his late 60 or 70 years old and he has gray hair which grows to his shoulders.
|Main Characters||Yū Otosaka • Nao Tomori • Jōjirō Takajō • Yusa Nishimori • Misa Kurobane • Ayumi Otosaka • Shunsuke Otosaka • Takehito Kumagami|
|Supporting Characters||Maedomari • Medoki • Shichino • Furuki • Sala Shane • Kazuki Tomori • Yumi Shirayanagi • Tsutsumiuchi • Konishi • Udō • Arifumi Fukuyama • Saitō • Iori Sekiguchi|
|Minor Characters||Mishima • Kōta • Shō • Nomura • Oikawa • Sugimoto • Takato • Yoshiyuki Ōmura • Mrs. Tomori • Gondō • Hosoyamada • Mr. Kurobane • Mrs. Tomori • Honoka|