2020，大學畢業之後，三笘返去川崎前鋒，開始左佢嘅職業生涯。喺第9輪到第11輪，他連續2場比賽都入到波，而且喺對北海道札幌岡薩多嘅比賽入面梅開二度。
In 2020, after graduating from university, Mitsuki returned to Kawasaki Frontale and began his career. In the 9th and 11th rounds, he scored in two consecutive games and scored twice against Hokkaido Sapporo Consadole.