He was educated at Tohoku Fukushi University in Sendai, same school as Hideki Matsuyama.

[3] Semikawa represented Japan at the 2022 Eisenhower Trophy at Le Golf National in France where he had the second lowest individual score, a stroke behind Tobias Jonsson of Sweden.

[4] In September 2022 he won the Panasonic Open on the Japan Golf Tour, setting a new amateur record of 61 in round three.

Afterwards he ascended to number one in the World Amateur Golf Ranking, becoming the fourth Japanese to rise to the number one position following Hideki Matsuyama, Takumi Kanaya and Keita Nakajima.

In 2023, he won the Kansai Open at Izumigaoka Country Club in Osaka, taking revenge for his final round collapse as an amateur the previous year.