The Japanese word for "Pipa Pipa" is pipapipa ピパピパ, a katakanization.
Another word for "Pipa Pipa" is komorigaeru コモリガエル.
Suriname Toad, Star-Fingered Toad, Common Suriname Toad.
Scientific name: Pipa pipa.
Beware: some kanji that are difficult to handwrite are easy to type on the computer, which may skew the usage statistics.
Wikipedia: Common_Suriname_toad (ピパピパ)