Tsukasa Tenma is a third-year university student. He was originally supposed to be there temporarily due to his muteness, but his math professor, Rui, was able to convince him to stay because he knows sign language. They've been secretly dating for a while now and obviously don't show it at university. Tenma can sometimes be frustrated by his muteness, as he wasn't born with it. He lives with his professor and feels more at ease because Rui understands his signs.