The ML and FL were childhood friends, they meet when the FL was playing dodgeball and accidentally hitting on the ML's face. She apologized to him and he forgave her.

they became close friends until the ML had to go on abroad.

(They both don't know their names and slowly forgetting their appearance) etc. no spoilers.

In their second meet the ML was playing dodgeball in PE time, when suddenly the ball came flying but instead of getting hit by it, the FL catches the ball with one hand.

They felt a familiar feeling on their existence but they weren't sure what is it.