In 2019 Harada played for the Japan Under 20s and in 2020 he signed with the Sunwolves for the Super Rugby season but did not make an appearance for the team.

Harada joined Toshiba Brave Lupus Tokyo in 2022 where he excelled. In 2024 and 2025, he won back-to-back championships with the team. They became the first side in the competition to defend their title. The 26-year-old was part of the winning team, playing alongside All Blacks stars Richie Mo’unga and Shannon Frizell. He made a total of 55 appearances for the Toshiba Brave from 2022-2025.

At the end of 2025, Harada signed with Moana Pasifika on a one-year sabbatical, for the 2026 Super Rugby Pacific season.

Harada made his debut for the the Japanese national team, the Brave Blossoms against England in June of 2024.

Moana Pasifika debut: Yet to debut