What genre would Fiction by Sumika (a japanese band) be categorized as?

Question

The song, for reference: https://www.youtube.com/watch?v=IKHGAuNaGuA

I hesitate to call the genre "J-rock" or "J-pop".

Answer 1

This is definitely based on 60s and 70s American pop rock. In particular, it sounds to me like the 60s & 70s era revival of the old music hall and vaudeville musical styles. The foundation is the music that was played in American and British popular venues during the late nineteenth and early twentieth centuries, but with an overlay of 70's lite jazz and funk. It has a theatrical sound reminiscent of 70s television specials.

Leo Sayer - The Show Must Go On (after the intro section)
The Beatles - Penny Lane
Dr Hook - Walk Right In
Mamas and Papas - Dream a Little Dream