A young teenage boy with ruffled blonde hair that almost reaches his ears and has red eyes. Seen as pretty handsome to others.
He often wears an orange hoodie under his standard school uniform.
"My life's goal is to create my two-dimensional bride!"
In the art club, he often draws 2-D 'waifu' and will always introduces his brides to fellow art club members, especially Mizuki Usami.
Despite his often irritating personality, Uchimaki has shown that he is a friendly person. He doesn't care what anyone else thinks of him even if they irritate or make fun of him.
As a member of the art club, he is skilled in drawing as shown when he got second place and later first place in the art competition. He is also shown that he can draw people who he only just met.
He was accepted on the Art Club despite his only interest is to draw the perfect waifu. He pass all the time in the club doing it and when he asks to Usami or somebody to be a model to his drawings, he makes it totally different or adds some cat ears and tails. Uchimaki does not perceive that Usami loves him, so when she is nervous because of some situation about him, he thinks she is kidding or just being weird.
It is shown that Usami harbors romantic feelings for Subaru. But he seems to be unaware of her feelings for him. Having these feelings, Usami acts slightly like a "tsundere" towards him. Besides that, Usami and Subaru seem to be on friendly terms and have a slightly complicated friendship.
- He planned to quit the art club early on but didn't. He claims this because he wasn't completely satisfied with what was supposed to be his final "bride", but decided to continue immediately after seeing that Mizuki Usami would be lonely.
- His zodiac sign is Leo.