Interesting game, good implementation of danmaku and dialogs.
After Sans I expected it to be more about references to other games rather than Touhou, since the mysterious book could have these references, but sadly there is only "Fight against your own equipment" sounds like it could be one.
Agree with people that some patterns are way too long, also maybe hard, at least for me. On some of these I was dying non-stop.
P.S. thanks for sharing that WIP of main theme on Discord, it was icing on cake that was delivered before cake ;)