Kōji is a regular patron of the Time of Eve café. He is a quiet, seemingly honest and unassuming individual who often appears a little absentminded. He has a strong interest in photography and is almost never seen without a camera, which he handles with particular care and attention. He is always accompanied by Rina, a woman he is deeply in love with, and the two of them are perceived by other customers as a somewhat unbalanced couple.

Initially, Kōji is believed by other characters to be a human. However, it is later revealed that he is an android, just like Rina. Neither Kōji nor Rina are aware of the other’s true nature; each believes their partner is human. This mutual misconception forms the central tension of their relationship. Their love story is a key subplot in the series, illustrating the blurred lines between human and machine emotions. Kōji’s motivations are driven by his genuine affection for Rina and his desire to maintain their relationship, even as he grapples with his own identity and the social rules that treat androids as mere appliances.

In the story, Kōji serves as a supporting character whose interactions with the protagonists, Rikuo and Masaki, help them explore questions about love, trust, and the capacity for androids to form genuine bonds. His role highlights the theme of unrecognized android identity within the café’s non-discriminatory space. Kōji does not undergo a dramatic transformation, but his relationship with Rina deepens as they continue to meet at the café, each trying to understand the other while hiding their own mechanical nature. His notable abilities include a knack for photography, which he uses to capture moments at the café, and the typically advanced physical and cognitive functions of an android, though he deliberately conceals these to appear human.