Toga goes into witness protection
Four years post-canon, Izuku has gone to college to focus on building a normal life as best he can, taking a teacher training course. No world-ending battles, no uber powerful villains, just lectures and essays. But while there, he sees someone who looks eerily familiar.
A dark-haired girl in the library, across the quad, sitting a few rows ahead in class. Her mannerisms, the way she tilts her head, there's a flicker of something that tugs at Izuku's memories. It's impossible though, she died in the war.
But the resemblance is undeniable. Toga Himiko is alive.
If she's here now, living a normal life, then Izuku should let it go... Shouldn't he?