The song, for reference: https://www.youtube.com/watch?v=IKHGAuNaGuA
I hesitate to call the genre "J-rock" or "J-pop".
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.