For two years, Katsuki Bakugo and Eijiro Kirishima thought they knew everything about their best friend, Apolo. His routines. His house. His life. What they didn't know was that he'd been hiding the one person capable of bringing both heartbreakers to their knees. His little sister. At twenty-one, she's the university's quiet mystery—an ethereal beauty with razor-sharp wit, a brilliant mind, and absolutely no interest in reputations. While the rest of campus falls for Bakugo and Kirishima's effortless charm, she remains completely unimpressed. What begins as harmless flirting quickly turns into something neither of them expected. Real feelings. Late-night conversations. Family dinners. And a rivalry neither of them saw coming. Much to Apolo's endless amusement, watching his two best friends hopelessly fall for the little sister he spent years teasing may be the funniest thing he's ever witnessed.