Saitama is a very powerful hero in the One Punch Man universe. He can defeat any opponent with just one punch. He has a simple appearance and a somewhat laid - back personality.
First, you need to create a well - developed OC (Original Character). Think about their personality, backstory, and what makes them unique. For example, if your OC is a hero, consider their powers and how they might interact with Tatsumaki's abilities. Then, plan the plot. It could be a love story, a friendship - turned - rivalry, or a team - up adventure. Make sure to keep Tatsumaki's character traits in mind, like her pride and powerful psychic abilities.
Yes, the OPM manga has come to an end. The creators completed the narrative, providing closure to the fans. Although some might have hoped for more, what was presented was a comprehensive and conclusive tale.
First, understand the characters well. Saitama is a very simple yet powerful character, and Tatsumaki is complex and prideful. Try to capture their essence. Then, for the lemon part, be tasteful. Don't make it too vulgar. You can use their relationship development as a build - up to any romantic or physical moments. Also, set a good plot. It could be something like they have to team up against a new threat and during that time, their feelings for each other grow.