Also,
The illustration at the end is made by the author/mangaka of a Manga called Hoshino, Me O Tsubutte.
What?? Not interested enough? Okay I cut you a deal,
apparently the artist have other pen name called "Ishigana" that they use when making doujin.
It’s weird - I could’ve sworn I saw a source for that, but when I looked again just now I couldn’t find it. Could just be an unbased rumor for all I know.