Not related to Haikyuu!

As the son of retired Japanese national team ace Shishiya Kei, Shishiya Gaku was the ace of his middle school club team, but he wondered if he was suited to be an attacker. One day, Kei came to watch Gaku practice and met Noboru, who had exceptional talent as an attacker, and declared that he would make him the best volleyball player in Japan. The father-son relationship ended. Gaku vowed to prove his own limits as an attacker and beat his father and Noboru with the volleyball style he had pioneered.