Seeing that this thing is completed with 9 chapters, i suppose it adapted the whole LN Volume 1 which was the main volume and it finished, just to the point lmao, though there is alot more standalone LN volumes, like 8
Something i noticed is that the publisher
France Shoin went hard to promote their Ero LN with shorts manga adaptations, since all of them ended pretty fast, between 3-5 chapters and this one going to 9