(Prince of Tennis) A Romance Sparked by a Phone Call

The female lead is a mixed-race girl and Sanada's younger sister. The male lead is Tezuka. Her grandfather is a godfather in the [redacted] underworld, and her mother is from the Sanada family.

The female lead and the male lead first met when she accidentally called the wrong number and reached him. This misunderstanding turned them from strangers into friends. They shared everything with each other, through spring, summer, and winter, and through every emotion, whether happiness, anger, or tears. No one could have imagined that a single phone call would make them fall for each other...