Has an NPB (Japan) game ever ended 15-2?
It has. 15-2 has been a NPB (Japan) final 31 times in 63,173 games. The first was Hankyu Braves beat Mainichi Orions on August 15, 1950; the latest was Yomiuri Giants beat Tokyo Yakult Swallows on August 19, 2025.
That makes 15-2 the 102nd most common final score out of 223 that have ever occurred in NPB (Japan). One point away, 16-2 has happened 21 times and 15-3 has happened 30 times.