When Tezuka defeated Fuji prior to him leaving for Germany, Fuji cried after Tezuka turns his back and leave knowing it might be the last time he might never ever get see nor play tennis with Tezuka ever again.
There are things that both Fuji and Tezuka will do for each other. One example being Tezuka granted Fuji's wish to play against Jiroh when Fuji found out he defeated his younger brother in a mere 15 minutes.
In the TeniPuri family episodes, Fuji is the sweet yet impulsive Grandmother of the family and is often paired up with Kunimitsu Tezuka, who plays the Grandfather. In the other Tenipuri chibi episode, settled in the Far West, he plays a damsel in distress-type girl searching for a Lone Gunman who later turns out to be Tezuka