[1] Hasegawa made his professional debut on April 11, 2021, at DEEP KICK 52 against Ryuzo Hashihiro.
[2] Hasegawa reached the final of the KROSSxOVER New Generation Cup on December 5, 2021, where he faced Shinichi Watanabe.
The fight was declared a no contest after a clash of heads opened a cut on Azusa Kaneko that forced the ringside doctor to stop the bout in the first round.
He won the fight by a third-round knockout with a flying knee and advanced to the finals where he would face Jin Mandokoro.
Hasegawa was defeated in the final by unanimous decision after suffering a knockodwn from a head kick.