A deer girl. That's not so common. Or more like a herd of deer girls. And they're all witches, too.
Kanoko actually proceeded to destroy the school. I guess sensei and the other witch girls magically rebuilt it before any real trouble could happen. The part I'm not sure about is whether they actually lived those dates while his memories were being manipulated to make him think he's her boyfriend, or were they just "realistic" but fake memories inserted into his head.
I like that he willingly chose to continue loving her even after she came clean with the truth. I'm just a little bit disappointed they weren't explicitly dating after everything including her sudden transfer into the school, even though they both know they like each other. Maybe the mangaka's hoping for a serialization where this becomes chapter 1 instead of an alternate story? Anyway, it's not bad and it's certainly cute.
On a side note, Kanoko reminds me a little of the utaite (& vtuber) Kano (鹿乃), whose image character is also a deer girl. I initially suspected the 鹿 (ka/shika) kanji for "deer" would be in Kanoko's name, but upon checking the raws I was wrong, her name is just かのこ "kanoko" with no kanji in it.