Socially Anxious and Accidentally Bound to an Otome System: The Tyrant Arrives in the World of Tennis

The protagonist's home team is Rikkaidai. I haven't figured out the blurb yet; I'll fill it in later. It's probably a story about a socially anxious protagonist bound to an otome System who takes up tennis by force to earn points, traveling around to challenge schools and check in at various places, until they become the shadow haunting the entire middle school tennis world.

Theme: The winner takes all.