[1] Born in Ushiku City, Hosoya started playing football in the first grade of elementary school, inspired by his father.

[3] Hosoya made his debut for the U-18s aged 16 in April 2018, when appearing in the Prince Takamado Trophy JFA U-18 Football League in a game against Júbilo Iwata U-18s.

[7] Whilst registered as a Type 2 player, in March 2019 Hosoya made his J.League debut in a 2–0 league defeat to Tokyo Verdy, coming on as a 64th-minute substitute for Yusuke Segawa.

[11] With both Olunga and Hiroto Goya leaving the club at the end of the 2020 season, Hosoya was afforded much more opportunity during the 2021 campaign.

By the end of the season, he had made 34 appearances and scored 8 goals and coupled with his impressive performances was enough to earn him the 2022 J.League Best Young Player award.

[16] He then made his first appearance for the Japan national under-23 football team in October 2021 as part of the qualification campaign for the 2022 AFC U-23 Asian Cup.

[22] Following a three-day training camp in Chiba in May 2022, later that month it was announced that Hosoya would be part of the squad for the 2022 AFC U-23 Asian Cup.

[28] On 13 July 2022, it was announced that Hosoya had been called up to the senior national team to take part in the 2022 EAFF E-1 Football Championship, alongside teammate Takuma Ominami.