Izuku dies. Katsuki doesn't know how to exist without him. (Luckily, he doesn't have to.) Izuku dies before Katsuki can tell him he loves him back. And after, when he fails to cope and realizes that a life without Izuku isn't a life he wants to live, the past users of One For All realize that this can't go on. There's only one thing they can do. At the cost of themselves, they give Katsuki the one thing he'd been wishing for: another chance. Or: Izuku dies. An emotionally compromised Katsuki Bakugo travels back in time and is going to save him no matter what. Even if he'll probably cry while he does it.