(NOTE: This UTAU is not finished, once I am done, you can use it however you want with, or without permission.)
Kanashii means sad, or upset. He is Kaarorin Kitto's brother, which is why his last name is an adjective or emotion.
Kai was chosen by the creator (TacoTaco Cat) because he likes the name and "Jay" (his name) cannot be written in Japanese.
Kai is a Japanese utauloid. He was created after Kitto Kaarorin on January 4, 2015. He is like any normal person his age, except he usually hates everyone.