This story is full of webcomic spoilers so don't like, don't read. The updates happen sporadically and usually when events from the original OPM webcomic will make sense to the story. I like to wait for canon material before I continue so yeah.
The main ship: Amai Mask/Saitama/Genos
Situation:
Saitama is the strongest hero in their universe but his tragedy is destined to happen soon. As such, the universe decided to grant him two soulmates who are suffering a clashing predicament that is bound to doom them to death. One of them has to die so he can continue his hero duties and live a happy life.
Byuuto (???) is an ugly man who upholds high morals and so he did good deeds by being beautiful on the inside. Back when the Hero Association is established, he destroyed his former identity and lived under a mask hoping to be his ideal hero. However, this mask turned him into a beautiful monster, thus dooming him to live in a cage of a false identity. Once this is revealed, everything will turn against his favor. Unfortunately, he can see his red string attached to Saitama but it is very clear to him that he has no place in his life.
Genos is a young boy who aspired to become a successful engineer who had his life turned upside down when Mad Cyborg destroys his city and kills his family. When he wakes up from the incident, he is horrified to find himself looking exactly like the Mad Cyborg that took his normal life away. He is already trapped in the cage of revenge, and once he finds the Mad Cyborg, everything will end for him. Unfortunately, he cannot see his red string attached to Saitama.
Then Maho and Rika changed their lives.
This series has three parts:
The Pain of Me and You (Saitama/Genos)
Saitama and Genos both go to an event organized by Amai Mask and know of certain things.
Status: Chapter 6/10
Next Update: Probably December 2020
At Least Let Me Have This (Saitama/Amai Mask)
Byuuto (???) goes back in time to change the timeline and replaces Genos in Saitama's life.
Status: Chapter 0/10
Next Update: Probably May 2021
Compromise Is A Word For Us (Amai Mask/Saitama/Genos)
Saitama realizes that this has been the millionth time this happened and changes it.
Status: Chapter 0/10
Next Update: Probably January 2022
I am a busy person and as much as I would like to finish it right away, I also have real-life problems. For now, enjoy what I post hehe.
