Senpai is normally a very polite and calm individual who typically speaks in a formal way, especially towards people he likes. However, he has a short temper and is a sore loser, becoming rude and speaking more vulgarly after losing. This sudden behavior change is explained as a result of Senpai's programming being unable to handle a loss since he was only ever meant to be perfect. (He Kinda Hates Girlfriend`s Boyfriend aka Boyfriend.XML and has a Crush on Monika from DDLC)