The Jack-of-All-Trades Prince of Tennis

Elementary school student Niou opens his personal stats panel: Strength 28, Speed 36, Stamina 32, Mental Strength 42, Technique 32. Niou: So your system uses a scale of 100? System: By the standards of middle school tennis on Earth, you can think of it as a 160-point scale. Players are rated from 1 to 8, and 8 or higher counts as professional adult level. Niou: ...160 points? So each of the five stats is actually... Wait, a Strength score of 28 works out to just 1? System: Correct. There's no rounding; the remainder is simply dropped. A 39 is still a 1, and you need 40 to get a 2. Or you could write it with a decimal point. Want to know the five stats of the opponent you beat 6–1 at a junior tournament? Niou: ...No, I don't. Shut up. No CP, System story, a conventional leveling-up adventure with a golden finger. Exclusive rights reserved. Reposting or reproduction prohibited. [Character OOC] warning. [Not fully researched] warning. [Rikkai dominates] warning. The main story is about all-powerful Niou and an undefeated Rikkai! The crossover worlds are just there to add to Niou's omnipotence, so feel free to skip chapters! 60% content lock, so keep that in mind when skipping around~ The pacing is slow, and it's expected to be a very long story, mainly focusing on matches (all kinds of matches) and daily life. The story is mostly about Rikkai, so Seigaku fans, proceed with caution. This is my take on the tennis world, so proceed with caution if you dislike OOC. Please don't mention me in other authors' comments, and don't compare authors or their works. Let's respect each other. Thank you. I've started stockpiling chapters for a second part. This story's main focus is tennis, and I want to write about other worlds, so I'm planning a sequel about adult Niou traveling to other worlds to save them. Most of the Demon Slayer story will be in the second part. If you're interested, please add it to your favorites~ I've also started stockpiling a basketball story, but I haven't settled on the main plot yet; I just really want to write it. I really love basketball! The story will probably be connected to the NBA. Theme: Only through tireless effort can you succeed