Mitsuya is a good-looking boy, commonly described as an "Ikemen". He has short blonde hair and brown eyes. In the manga, he also appears to have 2 piercings on the left ear.
Takanashi was initially snobbish, deceptive and arrogant to the point of ruining Hikari Tsutsui reputation just so he could have a chance with Iroha Igarashi by spreading rumors that Hikari was a lolicon. Later though, after witnessing the gravity of his actions, he begins to feel a bit of remorse and eventually apologizes to Hikari's family along with his younger sister who assisted him with this act. He eventually begins to tag along with Hikari and his group of friends more. He begins to act more like a friend to Hikari as the story progresses, and starts to care more about Arisa Ishino, although he continuously denied it. This hints to him having feelings for her, and plays into the "tsundere" trope.