
He took on his memories, not his personality. MC is the same guy as when he died. We never saw the other guy at all, not even in a dream. He is non-existent in this story. It's a little sad in body swap stories like "End of the Road" and all how the other person is just erased.
Even so, everyone else is incredibly accepting of his "back from the dead in another body" thing.

So from the very chapter that they swapped it was told that the other one die of overdose. When the seme saw the uke naked and awake he was surprised since he thought he had died from to much rush. This is a drug that isn't too common here in the us but for Asians it's just like saying he had an opioide overdose. So yes from the very beginning both bodies died and one took the place of the other.
In the beginning I questioned about the other guy too untill I re read and saw that I over looked that small conversation. Body swaps do suck though cause why does one get a new chance but not the other? I layers think that it's cause one tends to have a hand in his death while the one still alive didn't.
... of the idea of a body swap. And no one cares what happened to the other guy. Did he die and the other actor take his place? This is the problem with body swaps. You're always left feeling sorry for the person who was written out of their own body.
And wouldn't others want to know how that worked? Will he swap back? Will he suddenly disappear and the other guy wake up again. Everyone's all like "Yeah no worries. This magical phenomena is totally permanent because of reasons! The Plot will protect us!"
Oh well, I guess just enjoy the story. I like the characters.