I observed nine episodes of predation by juvenile Fejervarya kawamurai (20–24 mm snout-vent length [svl]) on Hyla japonica juveniles (14–17 mm svl) and froglets (18–34 mm total length) in a rice field in Kobe City, Hyogo Prefecture, Japan. In one case, a predatory F. kawamurai (23 mm svl) fully consumed a juvenile H. japonica (ca. 14 mm svl). In other eight cases, the predator partially swallowed but eventually released the prey. In some of the latter cases, prey was larger than the predator. Released prey exhibited various injuries from repetitive biting and pushing with forelimbs by the predators in an attempt to swallow the former completely. Fejervarya kawamurai has recently been expanding beyond its historical range, and effects of their voracious predation on other frog species in newly invaded areas would be of a substantial conservation concern.