Ozu is a Kyoto University student bound to the protagonist by "the black thread of fate." Their connection began freshman year when both joined the Railway Club, a group researching a fictional railway. Ozu's disruptive suggestions fueled infighting that collapsed the club, which later reformed without him and the protagonist. He subsequently became Akashi's fellow "disciple" under Higuchi in the film club.

He consistently exhibits mischievous and troublesome behavior. Accidentally spilling Coca-Cola on the protagonist's air conditioner remote during an apartment gathering initiates the central conflict. Ozu frequently manipulates situations for his own ends, convincing the protagonist to pursue morally questionable schemes or derailing vital time travel missions to hunt for trivial items like Higuchi's shampoo instead of retrieving the remote. During one time travel incident, he volunteers to test the machine and then chases the protagonist's past self, disregarding the plan.

His relationship with the protagonist is antagonistic yet interdependent, marked by physical fights, mutual insults, and a homoerotic subtext noted by others. Characters misinterpret their altercations as lovers' quarrels; Akashi once mistakes their shirtless whipping confrontation for a sexual act. Despite this friction, Ozu participates in the protagonist's attempts to repair the remote and later assists Akashi's film project.

In a future timeline, Ozu is implied to have married Hanuki and become grandfather to Tamura, Akashi's son. His legacy includes inadvertently inspiring the time machine's creation through his past misadventures.