Here is a description of the setting: Moi's two worlds are combined into one, Miyu picked up the protagonist when he was 5 years old, and Shirou's setting is the same as Yukinoshita. Moreover, other people don't know about Shirou's magic, and neither Eri nor Kiritsugu. The Shirou I wrote is very low-key, so don't comment if you don't like it.
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.