Jun Kamiwazumi has found grass courts difficult, recording 13–25 across 38 matches (34.2%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar.

At Grand Slam level (Wimbledon): Jun Kamiwazumi has struggled at Grand Slam level on grass: 5–9 (35.7%) in 14 matches. The best-of-five format and elite fields make this the toughest benchmark on this surface.

By format on grass — best-of-five: 8–12 (40.0%); best-of-three: 5–13 (27.8%). Significantly better in five-set matches — a strong physical profile on grass that tends to tell as matches and tournaments progress.

Best season: 1971 — 3–2 (60.0%) from 5 matches. The best single-season display to date — a useful reference point as the grass record continues to develop.