
Well, MC from "Again" has his face burned and life ruined. He was also deceived by other evil character. Which, Ido none experience that or similar to it at all. He found MC suicide, then also shot himself. He back to the past, supposedly fix everything. Ido has no karma retribution at all. Only a mental torture and dealing with pheromone. That mental torture is a form of guilt as he should experience, not a karma. His physics is fine, career is fine. He didn't have convincing suffering like MC from "Again" or any acceptable reason for doing such horrendous actions towards Sejin.

Ido got influenced too, the past is not all his doing - He was influenced a lot by his brother's lies, that's why in their present life he offed his brother early when he had the chance .. Same goes with Nokyung in Again, he was influenced by his "love" to Hyunjae..
(i searched their names so people won't be confused)
im surprised Ido is getting a lot of hate compared to Again MC who also did unspeakable things - i mean they are both got influenced into doing horrendous things that also resulted a death of someone, and also given a chance to redeem themselves for a second time..
i just hope you guys are just influenced because this has a lot of angst than Again and not because Ido is a top - im saying this coz ive seen a lot of comments on diff sites that this is their reason