|Anime debut||The Girl Genius' Challenge|
|Japanese voice actor||Yutaka Aoyama|
|English voice actor||Rob Mungle|
The Gentleman, as he is referred to both in the anime and the visual novel, is a man who initially appeared to be mysterious in Kotomi's arc when he one day approaches her out on the street, which scares Kotomi. Tomoya, Kyou, Nagisa and Ryou all see that Kotomi is scared of his presence, so they try to ask the man who he is; however he is reluctant to answer their question. Upon talking to him, they make the man go away for the time being, still not knowing how he is related to Kotomi.
One day as Tomoya is out by himself, he sees the man outside Kotomi's house and approaches the man, once again asking who he is. The gentleman answers that he used to be one of Kotomi's parents' colleagues, and that there's something important he has to talk to Kotomi about. He tells Tomoya a complicated story about the Ichinoses' research and their scientific discoveries. Tomoya doesn't really understand the man's stories, however the man leaves Tomoya with a message to Kotomi, "I don't expect you to forgive us, but we still regret what happened that day."
When he learns more about Kotomi's past in Hidden World, he finds out that the gentleman is actually Kotomi's official guardian as her parents died in a plane crash several years earlier. The man they all thought was a bad guy was actually trying to give her the birthday gift she was promised as a little girl.