Chiaki Mamiya is the deuteragonist of The Girl Who Leapt Through Time. Along with Makoto Konno and Kosuke Tsuda, he is a student at a local high school in the Shitamachi area of Tokyo, Japan.
Chiaki is seemingly a laid-back, lazy, and playful guy. He is close friends with Makoto Konno and Kosuke Tsuda and it is shown that he cares deeply for the both of them. It is revealed that he has feelings for Makoto, of which she is oblivious to.
At school he mostly hangs out with Makoto and Kosuke and is rarely seen talking to other students. He is often found playing catch with them afterschool. Chiaki is apparently quite intimidating. When he approaches his classmates to stop them from bullying Takase, they back off in a hurry, likely due to fear. When he mysteriously leaves school, it is shown that a lot of students are making rumors about him.
Chiaki Mamiya is tall in appearance with bushy orange hair. He is usually seen wearing the white shirt of his school uniform with a red tank top underneath.