Recommendations for Quick Transmigration, Anime Crossover, and secret-identity novels with male protagonists, as well as some female-lead novels with male love interests. My personal preference leans toward male protagonists.
The tags may not be accurate. They're based on my own tastes and understanding.
These are all books I've bookmarked. Honestly, I bookmarked a lot of them after glancing at the blurb and thinking they sounded interesting, without actually reading them. Of course, I've read most of them. There are lots of hidden gems whose titles don't give anything away, so I had to check them one by one. You might get lucky here and find something you like!
For example:
[Quick Transmigration] Love Tribulation, male protagonist, unsigned, ongoing. Although it's tagged Quick Transmigration, it's actually an Anime Crossover. The protagonist is a skilled actor and has transmigrated through 20 worlds so far. The current world is in a global collapse. The only issue is that updates are a little slow.
[Anime Crossover] Changing the World on a Whim, with Aizen as the protagonist. Unsigned, ongoing. It has over 700 chapters so far and updates regularly.
Mafia Scumbag's Handbook, male protagonist, signed, complete, with the second book ongoing. A big mash-up of Japanese anime worlds. The protagonist has had a lot of relationships, always breaking up before getting a new boyfriend. He's dated a company president, been a scumbag to Dazai, and flirted with Shuichi Akai and Gin, along with a few other anime characters. Those are the ones I remember best, though. So good!
Before Tragedy Strikes [Quick Transmigration], male protagonist, no pairing, signed. The protagonist transmigrates through different worlds, starting with small ones and gradually moving up to larger ones. Each world is pretty short, usually no more than ten chapters, and the worldbuilding rewards careful thought. The setting is incredibly grand. The protagonist takes things easy, and there are over 2,000 chapters so far. Content warning: In one world, he was forced to take the submissive role once, but they broke up afterward. He also transmigrates as a woman a few times, but there are no romantic storylines. There are tons of worlds, so feel free to skip any you don't like.
Theme: Never run out of books to read.
Now the author of the seven-character begging note has become self-proclaimed.