Shimizu Aki is a female tennis player and the reigning champion of the All Japan Junior tournament. Despite her age and shy personality, Shimizu is a very strong player, who had won the All Japan Junior tournament as a freshman. Her technique has no wasted movements, is fast and accurate. Shimizu first met Maruo in the Kanagawa prefectural tournament when Maruo picked up her phone battery when she dropped it. (Source: Baby Steps Wikia)