This is my the first time I completed, from start to finish without much problem, a light novel, after struggling with other novels like Kino no Tabi, Youzitsu, soshimin series, onajiyume (the only one here that was more readable was Kino no tabi, but it was tough).
The grammar is easy in the sense that the autor use the same through the book. It has some adventure like vocabulary, as well as some living in the forest-ish vocabulary.
Now, to listen it again with the audiobook
Easy to follow. I think is the easiest non-furigana manga i've ever read.
Contains some ecchi panels.
Love the art style.
Love the personality of the female protagonist (not so much of the boy, but whatever, is fun how he conducts sometimes).
Could be a bit slow, as the history is the kind of "waw, we just touch hands" and it shows the progress of their twist よだれ relationship.
A bit more difficult than the first volume
All the 組織 content is a bit harder to grasp, however, if you went throught the first book, the rest should be way easier. While I read the first book at an average of 2779 chars/hour --> 41h, the second book was at 4900chars/hour --> 35h The second book is way larger though. First book was about 115000 chars and second one was 175000. So good luck