Well the game has a few runners for what it's worth: https://www.speedrun.com/one_piece_world_seeker

But I'm not sure what you mean by a "popularity problem". If you want a lively community, then you need to run very popular games. There's really not magic advice to make a game popular. Most popular games are older games that are well known (Zelda games, Mario games, etc) or games that are a part of a long running series (Souls games as an example). One off games that are obscure or are really new probably won't have big communities because that's just the nature of games like that - they haven't had time to develop.

If you really want to work towards making a game popular, well, it's a lot of work and isn't guaranteed to succeed. But you'll need to start with working with the existing community and building from there up. Get good runs, get good times, try and get the game into marathons that will expose it to a wider audience, those are all things that can help with bringing more attention to a game. But at the end of the day, people will run a game that they enjoy or that interests them and in some cases, a game will only appeal to a niche group of people.

If you're only interested in this hobby to get popular, well, then that's just the wrong mindset to take in my opinion. Nobody should enter this hobby trying to get popular because in this hobby - like streaming in general - very very few people actually become "popular" and bring in 1000s of viewers. Instead, you should just approach it with the goal of having fun and competing to better yourself and your times. That'll be the best way to both enjoy what you're doing and to improve your times in whatever game you choose to learn.

Join the club. Personally I think it's better to play a game whose speedrun you enjoy, regardless of how popular it is. If you like the game enough, maybe it'll get a community, maybe it won't; but the chances that you'll stick with it long enough to be good are higher. If you're only looking to make a name for yourself, let's just say that's not happening. Popular games have so many runners that you won't stand out unless you're really good at them. Unpopular games are nearly impossible to be noticed at on their own merit. I'd love for more people to run my main game, but realistically I know my reach is limited as someone who prefers offline recording to streaming and isn't good enough to be noticed in any other games. What I do have, that people who enjoy the hobby the most do, is the desire to continuously drive my own times down.