So wanted to give a bit of info for this series. It is not a new spin-off, but an adaption of the Collection of Short Stories side volume for the original light novel. All the 2 chapter stories that will be covered in this were originally released as exclusive extras depending on where/which version of the volume you purchased. If you purchased the physical on TO-Book's store, you got one story (which this chapter actually came from for volume 1), but if you got digital from Bookwalker, you got a different bonus story (which will be chapter 3 and 4).
For this chapter specifically, some people might feel like they have already seen this in a manga, and that is because the spin-off adapted part of this.