けいおん!

I think it's the best first anime you can watch in Japanese

K-On is a story about Hirasawa Yui, A highschool student who joins the light music club.

The story is very simple, It follows the club members as they progress in life.

This is what the anime promises and this is what it delivers in a great way, And the characters are likable. And the music is just fire.

Now, In terms of learning, The vocabulary is general everyday and school vocabulary, With a few terms that you can count with your fingers regarding music.

The characters usually speak slowly and clearly, Although there are some comedic moments where that's not the case.

Personally I think it's the best anime you can watch if you want to get into native content without being overwhelmed by the sheer amount of specific vocabulary and unclear pronunciation.

I'd also recommend it if you just want a good anime even if aren't looking to learn Japanese