Anime Like 15-sai, Kyou kara Dousei Hajimemasu.
This one goes straight for the pulse point: Hiyori finally gets the apartment she has been dreaming about, and Soushi is already inside it, and then he kisses her before she can even unpack the question. That is the whole engine, and it is a mean, effective one. The show lives inside her head as she cycles through the only two options that matter, he is messing with me versus he means it, and every time she almost lands on an answer he moves the goalposts. "I was planning for us to stay just friends" is the line, and the childhood-friend-turned-predator flip is exactly the flavor of romance that gets called trashy by people who then read all thirty episodes in one sitting. No side plots, no school-festival detours, just proximity doing the damage. If you have ever wanted a show to skip everything except the part where your heart drops, here it is.
SYNOPSIS
Hiyori finally moves into her own apartment after starting high school, ready to live independently and away from her overbearing family. Her plans crumble when Soushi, her childhood friend, shows up unannounced at her door. Without warning, he kisses her and announces he's moving in. Hiyori can't tell if he's joking or serious, but Soushi refuses to leave, forcing them into an unexpected cohabitation. Living together transforms everything between them. Soushi's constant presence and bold affection challenge Hiyori's perception of him as just a familiar face from her past. She finds herself noticing things she never cared about before: the way he looks at her, how deliberately he pursues her attention, his refusal to back down. Hiyori's heart races in ways she doesn't understand or know how to handle. What starts as confusion becomes something far more complicated. At fifteen, caught between irritation and attraction, Hiyori must navigate living with someone who won't let her maintain comfortable distance. Soushi's persistence forces her to confront feelings she didn't know existed.
