Yeah, he wakes up after falling asleep only to find himself, perfectly in the right mind and still capable of coherent words. Later on, he theorize that the antibody in his body was able to fight back the zombie virus.
The Indonesian translation is up to Ch65 and I haven't finish reading it but so far it isn't fully explained yet as to how Hohyun were able to fight against the zombification.
Apparently, Hohyun thought back about the times Youngwon have seen him dies and realises that there were not one route at all, whereas he dies from becoming a zombie.
So, he came up with the idea that the reason why Youngwon have been returning back to the start each time Hohyun died was because he needed to make Hohyun, who is immune lives till the end.