Virion Kisei is a parasitic slime that had always wanted to be a human, or more specifically an idol and a singer. Unfortunately for him, his kind does not possess lungs, vocal cords, or even mouths to speak of. In his bid to fulfill his dream, he began traveling around the world for centuries to find the perfect host. Eventually, he came across a human city, and possessed a human being that had no acquaintances and relatives to speak of.
Coincidentally, the human he possessed also wished to be an idol but had long since given up on this dream due to circumstances. Virion, wishing to fulfill his host’s long lost dream eventually decided to become a Virtual YouTuber so that he could start from the basics and be connected with other fellow human beings, and to improve himself as an idol to eventually become the best idol, like his host wished to be.