Appeared in chapter 22, Tomoyuki made his first appearance through a voice message in his father's answering machine. He indicated in his message that he wishes to take care of Fumino and Teppei since his work has become less busy. It is revealed in chapter 23 that he is the younger brother of Fumino and Teppei's father, and is therefore Fumino's uncle. He wanted to take away Fumino and Teppei from Kazuma so that the secret of their marriage will not be revealed. Tomoyuki forces Fumino and Teppei to leave Kazuma's apartment and live with him. He believes that Fumino and Kazuma will grow apart since they won't be seeing each other as often. He is relatively short for a guy and has a slim build, and he's extremely baby-faced; He looks as if he's still in high school even though he is 28 years old. Fumino has stated that she has spent time with him since she was a little girl, and in all the time that she's known him, his face hasn't changed. Despite his appearance, he is very strong, and is something of a legendary Judo practitioner.
From Wikipedia