High school Shiogai played on Buddy SC Koto (U-12), and on
Yokohama FC U-15s. On Yokohama FC, he barely played, and failed to win promotion to its U-18s. He stated that he wanted to win the national tournament, and being its top scorer, prior to the start of the tournament. Participating for the first and last time on the national tournament on 2023, the then-third grader scored a goal on its first match, against Kindai Wakayama, qualifying them to the third round. In a difficult match against the eventual champions Okayama Gakugeikan, he failed to score on the 0–0 draw and missed a penalty in the 5–3 shoot-out loss. Despite the loss, Shiogai was noted as one of the nation's best prospects, and selected as one of the 36 best players of the tournament. As expected, he was selected for the Japan High School squad of the year. Representing them, he played the "FUJIFILM Super Cup Next Generation Match" against the U-18s of
Yokohama F. Marinos, scoring a brace, and participated in both the Denso Cup Challenge and the U-19 Youth Soccer Tournament in
Düsseldorf.
University and Yokohama F. Marinos Shiogai joined
Keio University on 2023, studying on the Department of Political Science, Faculty of Law, and playing for its football team. He was gifted the number 10 on his first-year, before changing to the number 9 on his second. On 10 April 2024, he made his debut for Marinos against
Gamba Osaka in a 2–0 win, in which he was subbed on at the 67th minute. He started a match for Marinos in their following match, played against
Shonan Bellmare. Making a lasting impression, he played 57 minutes, scoring his first professional goal on the 21st.
NEC On 28 August 2024, Shiogai signed a four-year contract with
NEC in the Netherlands, joining his compatriots
Koki Ogawa and
Kodai Sano at the club.
Wolfsburg On 20 January 2026, Shiogai joined
Bundesliga side
VfL Wolfsburg on a four-and-a-half-year contract. ==International career==