Why is Hikari's nickname "Pikari"? In Episode 1 of Amanchu!, Hikari states that her nickname is Pikari. In the English subtitles, she offers this explanation





  Hikari: Due to my overly peppy nature, people in junior high called me "Peppy Hikari", "Peppykari", and finally just "Pikari".


Where does this name come from in the original Japanese?
In Japanese, Pikari (ぴかり) is one of the numerous mimetic words of the language, meaning "in a flash"/"sparklingly"/"brilliantly", mostly associated with thunder and lightning. (Also, Hikari itself means "light", but I don't really know if it's related or not.)

Given the energetic and cheerful nature of Hikari, it's a fitting nickname.

Some references :


https://en.wikipedia.org/wiki/Japanese_sound_symbolism
http://jisho.org/word/%E3%81%B4%E3%81%8B%E3%82%8A