Kageyama Tobio is a first-year student at Karasuno High School and plays as the starting setter for the boys' volleyball club. He was chosen to train at the All-Japan youth training camp during his first year of high school and joined the V. League as soon as he graduated. He became a part of Japan's national volleyball team at the age of 19, participating in the Rio Olympics in 2016. In November 2018, he was playing as a setter for the Japanese V-League Division 1 team Schweiden Adlers.