Shinobu Takatsuki (高槻 忍 Takatsuki Shinobu) is an 18-year-old high school student, (and the son of Mitsuhashi University's dean of literature and of Miyagi's and Kamijou's boss) who believes it to be fate that he is in love with his ex-brother-in-law, Miyagi Yo. He would very much like Miyagi to take responsibility for Shinobu falling in love with him. He is often blunt and unreasonable, always going with emotions rather than logic, though he is shown to have a softer side. In the anime adaptation, he is voiced by Daisuke Kishio.
After hearing that his sister divorced Miyagi, Shinobu rushes back to Japan to meet with Miyagi in order to reveal his feelings for him, and ask him in all seriousness to "take responsibility" into the matter. Miyagi is shocked and believes the young boy is insane, but he soon discovers Shinobu is very serious about it and ready to do anything to claim his love. He initially tried many attempts, even at some point on the brink of leaving Japan, to show Miyagi how much he loves him.
Shinobu is a high school (now college) student. He is not very patient when it comes to promises. He is always seen wearing his school uniform.
Shinobu first introduced, returning to Japan from Australia after finding out about his sister's divorce with Miyagi.