Japanese pop. Not as straightforward as J-rock. There are a lot more influences, just like in ‘plain’ pop music. Pop stands for popular, so it can actually be anything and everything that’s the norm. J-pop has influences from traditional Japanese music, rock (and hence blues, etc), synth-pop and city pop (that in turn has influences from funk, R&B and boogie, among others). Well, it’s a little bit of everything and it is often used as an umbrella term.