Height 167cm (5'6") The main deuteragonist of the story and also Nana's love interest. Currently goes to college and is aiming to become a civil servant. She spends most of her time in her room playing video games. The author, Manio, describes her character as "無自覚クズ" or "unconscious scum", someone who is generally a bad person but isn't aware of it themselves.

Spoiler

After hooking up with Nana she reveals to her that she actually has a girlfriend named Yumi, who she has a rather complicated relationship with. Yumi is a very possessive girl, who doesn't like it when Tsukasa hangs out with people other than her. Due to this, she has tried breaking up with Tsukasa multiple times, only to come back to her immediately after. Tsukasa says she doesn't want to break up with her either, as Yumi is the first person she's ever truly loved.

Spoiler

She later talks Nana into blocking some of her online friends.