One rock band that I enjoy, and think would be good for Japanese learners is: 打首獄門同好会 (Uchikubi Gokumon-Doukoukai)
The songs are just about every day life, and the lyrics are written simply. At my current level, I often find that I can't follow the lyrics to most Japanese music, but with Gokumon songs I find that I can follow a lot of it, which is a rare treat.
I dunno if it's been mentioned yet, but Japanese city pop is really good if you like 70s/80s style funk/pop. Lots of nice guitar and saxophone solos, and great for chilling/dancing/studying. It's easy to find all over youtube too. A lot of people report a nostalgic feeling listening to it, despite never loving in 80s Japan, and I totally get it.
Tatsuro Yamashita, Mariya Takeuchi (they're married!), Miki Matsubara and Takako Mamiya are my favourites. A lot of nice mixes out there on YT to check out to find more artists. Tatsuro has a few english songs too, so you can sing along the them if that's your native language!
