Has an NPB (Japan) game ever ended 20-3?

Exactly once. On September 18, 1994, Fukuoka Daiei Hawks beat Chiba Lotte Marines 20-3, and no NPB (Japan) game before or since has ended that way. When it happened it was a scorigami, the first 20-3 in league history.

Where 20-3 sits among nearby NPB (Japan) scores. Deeper blue means a score has happened more often; the outlined cell is the new one.

That makes 20-3 the 191st most common final score out of 223 that have ever occurred in NPB (Japan). One point away, 21-3 has happened 5 times and 20-4 has happened 8 times.

Every 20-3 in NPB (Japan) history

Date	Result	Season
1994-09-18	Fukuoka Daiei Hawks over Chiba Lotte Marines	1994

Open the NPB (Japan) grid at 20-3