[1] Watanabe came second in the 10,000 metres T54 race at the 2013 IPC Athletics World Championships.

[2] Watanabe won the 2017 Tokyo Marathon,[3] beating race favourite Marcel Hug.

[1] In the same year, Watanabe finished third at the 2017 New York City Marathon.

[1] At the 2017 World Para Athletics Championships in London, Watanabe, Tomoki Suzuki, Yuki Nishi, and Hitoshi Matsunaga won the 4 × 400 metres relay T53/T54 race, by virtue of being the only finishers.

[5] Watanabe came second at the 2020 Tokyo Marathon behind fellow Japanese competitor Tomoki Suzuki.