I'm not sure if this is considered to be canon or not, but in my mind and my heart, I fully accept it as such. This is extremely engaging and a very good read. If you are a fan of Eromanga-Sensei, you see Elf in a whole new light and learn to love and appreciate her so much more. The art style in the food is incredible, which is essentially what this manga is about - about how Yamada Elf is an amazing cook and how she develops her friendship and opinion on Masamune, in more detail than what the original manga shows.