[1] He plays for Power Volley Milano and the Japanese national team (Ryujin Nippon).

[2] Otsuka started to play volleyball at the 3rd year of elementary school by entering in Panasonic Panthers Junior club.

Then, in the six grade, he attended at "JVA Men's and Women's Elite Academy Training Camp" held by Japan Volleyball Association, in order to find the future players for the national team.

In 2020, Otsuka had the name in the senior national team for the first time and he was one of the outside hitters in 2020 Summer Olympics.

[3] In 2024, Otsuka signed with Allianz Milan and will play for the team in the 2024-2025 club season.