I have read FAQ that described some songs/artists may not available in some countries.
I think It's ok if some Japanese artists are not available in another countries Spotify
but how weird is it if some Japanese artists are not availble in mainland Japan but available in another countries? such as Kana Nishino, Mariya Nishiuchi, Sayaka Shionoya, and Perfume are available in Singapore or Taiwan not in Japan!
That's why I'm not subscribed premium plan because some day I may need to move out of Japan to listen some Japanese songs in another countries (lol)