He won the Canadian Open by defeating United States player Walter Wesbrook 3–6, 6–3, 6–1, 11–9.

At the 1920 Summer Olympics held in Antwerp, Belgium, Kashio was defeated in the third round of the singles competition.

However, paired with Ichiya Kumagae, he won the silver medal in the men's doubles event.

In the doubles final, Kashio and Kumagae lost to Oswald Turnbull and Max Woosnam of Great Britain: 2–6, 7–5, 5–7, and 5–7.

Kashio was a member of the first Japan Davis Cup team, which finished as runner-up in the 1921 International Lawn Tennis Challenge.