I have seen websites which state that the name, 'Piyo' means a chick or the sound that a chick makes (chicks make this kind of sound?!!). However when I check the dictionary, it says that 'hiyoko' is a chick and there is no such word as 'Piyo'. Does that mean Piyo Piyo should be called as 'Hiyo Hiyo' instead? Anyway, the word 'Hi' and 'Pi' has little difference in terms of writing, 'Pi' is actually written as 'Hi' plus a 'o' as the superscript (see below).
Piyo Piyo is often seen with its other friends, like the butterfly, Cho-cho san (the name simply means butterfly), the caterpillar (it is always seen lying beside Piyo Piyo but I wonder about its realtionship with the butterfly, Cho-cho san), the dragonfly, and the snail. The first time that I saw Piyo Piyo was in a gift shop in 1995. At the first look at it, I thought it was a chick but then I saw a tag, which says: 'Little Yellow Duck'. Since then, I began to like Piyo Piyo. After that, I have bought and received a few merchandise of Piyo Piyo, for example keychain, pencil case and bag (hmm..., maybe my next target is the milk bottle. Heehee... ^_^ ).