You won son! OK brick joke done, now for actual comment.
Even if it's more of a book than a game, I think it's nothing short of absolutely fantastic.
The story in there took me for a ride I'll most likely never entirely forget.
To say it all in a single paragraph: the storytelling and the dialogues kept me fully invested from start to finish, every moment was interesting (both the serious and the more laid back things), the characters are quite fleshed out (going as far as filling some blanks for Kana and Kotohime, while keeping in character for everyone!) and so I couldn't help but care about the main cast.
One thing I'd like to bring up: in my opinion Reisen didn't feel like she stood out enough, especially when she ended up being Kana's partner. For you see, Kana, Kaguya, and Mokou got a lot of screen time where we see their character develop, but Reisen I felt was just there. She did have some moments where she was brought in most of these times, but I'd have loved to at least see more of her side, or a bit more into how her story with Kana turned out. All I know is that years passed after they first met, and now they're sweetey-lovey. Maybe having it all in the Rabbit Princess's perspective didn't quite allow for that, so that's understandable.
tldr: Reisen despite of feeling like she's in the main cast, doesn't have enough shown character exposition and development. I could give a 6 out of 5 in Writing otherwise.
Anyway, I go through the conversations, witness everything that happens in Eientei, and then I reach the epilogue. And it's fair for me to say the twist there is a shocker. It hit me like the truck that honked three seconds too late and sent me to the [Repairs Department] for months (for legal reasons, this last sentence was a joke).
The following is encrypted in ROT13 because it discusses the Epilogue (PatchMixolydic below had a great idea so I borrowed it):
Naq jura vg jnf nyy bire, V unq znal dhrfgvbaf yvxr "Jung'f gur qrny jvgu gur cneragf + freinagf guvat", "Jung vf guvf ceboyrz fur unf gb gnpxyr ol urefrys?", "Jung jnf nyy ure npgvbaf hagvy abj sbe, gura?", "Jung ernyyl unccrarq gb ure?", naq znlor fbzr bguref V'ir lrg gb unir cbc hc va zl urnq.
Arrqyrff gb fnl, fur yrsg oruvaq n ibvq bs zlfgrel, naq V pna'g fbyir vg. Abj V qba'g xabj vs gung'f orpnhfr V fbzrubj zvffrq fbzr favccrgf/ersreraprf nobhg gur Enoovg Cevaprff, be vs vg'f cheryl vagragvbany naq vg'f gurer gb or crefbanyyl vagrecergrq... V guvax V ng yrnfg jnag gb xabj juvpu vg vf, fb V pna unir n pyrne pbafpvrapr (vs lbh cyrnfr?).
V jrag gb yhapu, naq V xrcg ercynlvat gur fprarf va zl urnq, fgvyy guvaxvat nobhg gur Enoovg Cevaprff'f qrcnegher. V guvax nobhg ubj zbfg bs gur tnzr jnf sebz ure crefcrpgvir. Gura V erzrzore guvf vageb nobhg jung yvivat vf, naq gura nobhg Xnan, Xnthln naq Zbxbh'f onpxfgbevrf. Gurer jnf n ovt gurzr bs "ybaryvarff" va gurz - Xnan pnzr vagb rkvfgrapr gunaxf gb n ybaryl tvey naq pbagvahrq rkvfgvat va ybaryvarff, Zbxbh jnf n fbpvny erpyhfr sbe n zvyyravn, naq Xnthln unq gb bhgevtug vfbyngr urefrys sbe nf ybat. Naq gura V jrag "Ab... Qba'g gryy zr..."
Sbyybjvat guvf genva bs gubhtug, gung'q zrna gur Cevaprff gbb jnf va ybaryvarff. Ybaryvarff jbhyq or ure pntr, znxvat ure jvfu sbe ure cneragf naq bs n furygrerq yvsr fur arire unq (juvpu jbhyq or jul fur fnlf fur'f n cevaprff), Fur jrag bhg bs ure jnl gb trg bguref bhg bs gurve bja ybaryvarff, naq gung cebzcgrq ure gb iragher bhg nybar ba n dhrfg gb trg evq bs ure ybaryvarff.
... So was I supposed to theorize or did I overthink it? lol
But thank you for the read, it's been food for thought at a personal level. I can't believe this was your first time writing a story that long and (quite honestly) emotionally captivating. Your first Touhou fan story at that? I would have said I'm speechless but I wrote all this text so... ¯\_ (ツ)_/¯