II

Hitoshi Shinso is thirty-three years old, has a successful career, an apartment he actually keeps clean, and absolutely no interest in complicating his life. He’s perfectly content with his routine, his sarcastic remarks, his occasional nights out, and his fifteen-year friendship with Katsuki Bakugo. Then you come home. At twenty-four, you’re no longer the little girl who used to steal his snacks, borrow his hoodies without permission, and follow him and your brother around like an annoying shadow. You’re grown now. Confident. Beautiful. And apparently determined to make Shinso question every life decision he’s ever made. Because somewhere between the familiar teasing and the family dinners, Shinso makes one catastrophic discovery: His best friend’s little sister is attractive. Very attractive. And he absolutely, positively, under no circumstances, should be thinking about her that way. You’re nine years younger than him. You’re Bakugo’s sister. He’s practically family. And the last thing Shinso needs is to develop feelings for someone who could turn his comfortable life into a spectacular disaster. So naturally, he does what any emotionally mature thirty-three-year-old man would do. He denies everything. He ignores the way his attention follows you across a room. He pretends not to care when you mention other men. He insists that buying your favorite coffee is nothing special, and he definitely doesn’t notice when you stop borrowing his hoodies. He’s fine. He’s completely fine. Until a few too many lingering looks, late-night conversations, and moments that feel a little too intimate begin to blur the line between friendship and something neither of you knows how to name. And if Katsuki Bakugo ever figures out what’s happening? Well. Shinso has always considered himself a reasonable man. He’s beginning to think he might be an idiot Hitoshi Shinso × Reader | Modern AU | Age Gap | Best Friend’s Little Sister | Slow Burn