Check out interesting sub-niche: Japanese manga series. QuickAppNinja game developer from Singapore earned 318 USD with just one game "Demon Slayer Quiz".

You can download & try the game from Google Play - https://play.google.com/store/apps/details?id=com.kylertan.demonslayerquiz

We are HIGHLY RECOMMEND to the game developer to add more levels! With 128 levels he was able to made $318, but if he will double amount of levels - he probably double revenue. Math is simple)