"Kiya Kiya" is a word taken from the old Japanese word "heart-throbbing". I came across this word in the volume "About Toddler Experience" in Tatsuhiko Shibusawa's "Introduction to the Girl Collection". Knowing the existence of these words that express the mood of "déjà vu" and "feeling of nostalgia and anxiety that is hard to explain" was the catalyst for the production of the "Kiya Kiya" series. I did.
Source: Official Site