I know a lot of people says that choose material for immersion by level is bullshit, but if you is not one of those persons, this can be interesting. This website allows you to search for books and mangas by difficult level of user reviews (L0 – L41+), where more low the value of L, more easy it is. Here is the link:
[https://learnnatively.com/resources/search/?min=13&max=19&jlpt=n4&type=manga](https://learnnatively.com/resources/search/?min=13&max=19&jlpt=n4&type=manga)