Katsura

was a friend of Tenma Izumo during their time in Konohagakure's Academy.

Background
Katsura's father died during the Nine-Tailed Demon Fox's Attack, which many believed to have been the doing of an Uchiha. For this reason he joined Tenma and Hajiri in bullying Itachi Uchiha, though he was secretly afraid to face Itachi. Despite being much younger than all of them, Itachi easily defeated them once a fight broke out.