How to find the full version of a song Recently I've heard the song Play The Game's by Asaka, which is the ending theme of the visual novel Occultic;Nine. 

But I can neither get the proper full version of it in YouTube, nor a proper download link. How to find the full version of a song like this one?
As far as I can tell, the song is not available on Spotify although a few of Asaka's other singles are. Additionally, it looks like the single is for sale on the Japanese iTunes, but possibly not elsewhere.

Your main legal option, it seems, is to purchase a physical copy of the single. It is available on CDJapan and Play Asia, and possibly other import sites (but not Amazon US).