Taichi is Chihiro's father and the person who's the closest to him, resulting in him becoming Chihiro's captive for Killing School Life's first motive. In Taichi's character profile, it's mentioned that one of the things he likes the most is his child.
The two don't reunite after their kidnapping due to Chihiro's death in Killing School Life and Taichi's presumed death (or at least disappearance) in Demon Hunting. Before his death/disappearance, Taichi had no idea that his son died and was trying to reunite with him.
Taichi, just like his son, possesses some skills in programming. It's also worth noting that Taichi seems supportive of his son crossdressing as a girl in order to cope with being mocked for being weak.
In the bonus mode of New Danganronpa V3: Killing Harmony, the Ultimate Talent Development Plan, in Chihiro's event with Hiyoko, Chihiro mentions his father sent him a present to school and was emberrased about it. Hiyoko, being jealous of Chihiro's close bond with his father, told him to either accept it or throw it away, motivating him to accept the gift.
Fujisaki family also includes Chihiro's mother. However, not much is known about her. Chihiro appears to have a closer bond with his father since his mother wasn't chosen as his captive for the motive.
- “I have a child, y'know... You guys are all around the same age... But we got separated, and... A-And all this time, I couldn't do anything... I... I wasn't able to see... Just one last time... That's my only regret...”
- — Taichi's last words.
This familyship tends to get forgotten by most Danganronpa fans. The reasons for that are originating from a spin-off game, as well as Taichi's very short screen time. Nonetheless, it was welcomed warmly by the fans thanks to Taichi caring a lot about his child to the point of his last words being about his son and supporting him with keeping his secret.