...Well, at least he's honest. He literally shouted that he was lucky enough to catch her masturbating, whereas most protagonists might pretend that they didn't look or something similar. I like this guy.
I also found his thoughts partway through about what he did wrong or what he should be doing to be rather interesting too.
Great ending. Heh, jump out and surprise her? Why not? I'd certainly want to see her reaction...
Great art! One of my favourite artists. Good enhancements of sexual dichotomies rather than its lack--found in a lot of shoujo-style artwork. Great attention to detail and the ero action is intense, which seems to be lacking in a lot of vanilla ero manga.
I don't even know what is greater: the glasses girl aspect, the bondage aspect or the artist being Survival Knife. We definitely need more Survival Knife stories. And more bondage stories. And of course more glasses girls! Best would be tons of sequels to this and the artists previous story... By the way: why doesn't this story have a glasses tag?