[2] In junior high school, Morooka played for FC Tama alongside Ikuma Sekigawa and Junma Miyazaki.
[6] However, in November the offer was cancelled as Júbilo had been prohibited from registering new players by FIFA for two transfer windows due to a breach of contract involving Fabián González.
[7][8] This allowed J1 League club Kashima Antlers to offer a contract immediately following the announcement, to which Morooka accepted.
On 8 March 2023, Morooka made his debut for Kashima in a 1–1 J.League Cup draw with Kashiwa Reysol, appearing as a second-half substitute for Ryotaro Araki.
In his second season, Morooka was afforded much more game time under new manager Ranko Popović and has been a regular member of the starting XI.