Yuu Setoguchi 瀬戸口優

Yu's a boy that gets along easily with boys and girls alike, and is generally seen as a "cool" character. He's not one to anger easily, and keeps a cool head when he's around his more energetic friends. He doesn't wear his emotions on his sleeve, but sometimes they slip out in muted ways.

When it comes down to romance, he does get naturally fixated on Natsuki and watches any potential suitors to her with suspicion. Though he takes his relationship with Natsuki for granted, he is still possessive of her, citing their history as childhood friends as the reason why. He still wants her to come to a decision on relationships without others influencing her.

Because of his experiences with Hina, Kotaro, and Natsuki, he's adopted a nurturing image that reportedly makes him look "more mature".