This is more of a sidestory than an actual sequel since it goes into detail of how Mijima took the girl's virginity. Even though it takes place after the first book, that's just a framing device. I was hoping see how the relationship between the previous MC and the girl had changed and if she still liked the MC. Or even if the MC still works there.
BTW,there seem to be more works from Arakure which are Fanbox-restricted and not uploaded to this site. We request concerned users to bear this in mind should you encounter available resources.