Bring in the NPCs to explain what happens, and then have them argue among each other. This is probably the main reason there are so many side characters.
So, if the goal is to make the other drop the ball first, and they can pass, it means they're using tennis rules, as whichever ball is on their side counts for them if they drop it.
Takao is effectively three players at once.
They've not done that for too long, though. Just some 159 and a half chapters.
Don't hurt the MC's sister. That's going to bring the entire harem against them. For good reason.
Yeah, it's how you enjoy it. Or just tag along for the ride.
Out of everything crazy and potentially annoying in this manga, that's your straw?