He gave his last name to Tomura which is Shigaraki, but what if to hide his identity he merely changed up his name a bit before he was beat to a quirk stealing potato.
Hisashi Midoriya = Hisa Shigaraki
The name Hisa apparently means “long time, old story” depending on how it’s written it also means “long life”. This could target towards all for one’s lack of aging as he’s been around for years, if he merely was thinking up the name on the spot while meeting Inko he probably thought up the last name while noticing her Green hair. This is just a silly theory that makes some sense I guess