You know what, good for them. Make up for all that lost time.

Base +7

This would make a pretty decent little anime. Though I'm sure there's been similar. They bury their feelings while competing trying to move on from each other and then in the final handful of episodes you get all the lovey dovey payoff for your wait.

Base +6

this needs prequel...

is the senpai a virgin? why is he only looked at as a dildo by the other girl?

I need answers

Base +5

timeline question, so missed opportunity for 10 years, how old is this girl? shes a sempai, so still in school? assuming college this is what 12-22 ? 15-25? she looks 16 to me so initial guess is he wanted to bone her since she was 6.

Base +7

I'd say early mid twenties is the best bet. They just won a world competition likely at some major Tennis event or even the Olympics. So they'd have been teamed up in middle school through to the current day. The other girls shown would be other Japanese competitors on the world stage they spend time with at events or even train with.

Base +6, jsnormandy +10