Any ideas, anyone?
The back of my mind, it screamed of Koakuma. But later on, Meiling.
There's no logic behind it, just a gut feeling.
Meiling wasn't interviewed that much anyways.

Oh, I remember this thing. The answer is on the circle's website

Short form: It was Marisa, who'd made a trip before the one we see. Meiling moved the body

Oh shit... That was... was... so ... I can't explain my surprise at that.

Oh shit... That was... was... so ... I can't explain my surprise at that.

Want a lengthier explanation?

Oh shit... That was... was... so ... I can't explain my surprise at that.

Want a lengthier explanation?

I used google translate. Made my head all funny. Those translation ugh...
But if I understood right, Meiling dozed off the whole way, lying about her being fully awake.
Sakuya, Remilia, and Flandre didn't do it.
Marisa began her monologue like it was night but since it was Japan, the sun sets early.
Marisa changed her clothes, returned, faked that the doors were locked by bashing through the door.
When Meiling saw a dead Patchi, she moved her because she didn't want to get fired.
Marisa killed her, but I don't understand or remember more since google translate was a bitch.

Oh man, the seemingly mistake in the translation totally threw me off...
Sakuya said that Shameimaru arrived at "half past 6" in front of Remilia's door and interviewed her, which would give Shameimaru one hour after ending the interview with Meiling. But in the timeline it is correctly stated to be half past 5 instead of 6, so there is no gap.
But what I don't understand :
if only the murderer is allowed to lie, why does Meiling say that "between 10:00 and 17:00 no suspicious person entered the mansion"? And "Marisa arrived at 20:00". Since she was put on guard to keep Marisa away, it is clear to me that she did not tell the truth. Sneaking into the mansion is ruled out as far as I understand.

Ah, I also suspected her, but I wasn't sure. I could tell from Reimu's words though and I just inferred that she was the culprit.... She was on the top of my list while I tried solving things, but with such an explanation like the one given up top, it really makes me wonder about why the culprit had done the crime. Why did she want to kill her? Not exactly want though since Reimu mentioned stuff like that.

I read through that one messy whack of translated dialogue and was confused as fudge (cause of the amazing translation). But I never really do know though... Maybe I'm just being dumb right now, oblivious to the reality of the situation, or acting like a child but there are some things you can't know, I guess?

Also, this case literally makes Patchy a Locked Girl.

I'll never get enough of policewoman Reimu and Yukari.

But overall I am not much of a fan of how this was supposedly resolved, but first what I initially concluded before reading the spoilers above:

• Assuming Patchy didn't commit a miniscule amount of tomfoolery, there are 6 suspects: Remi, Flan, Aya, Meiling, Sakuya and Marisa
• We know the SDM is quite large, and crossing it on foot takes quite a while. We have confirmed mutual alibis for Meiling-Aya at 17:00 and Sakuya-Aya at 17:30. (Since ③ excludes any timestop shenenigans, it should be impossible to commit the murder and change in time for Sakuya).
• Remilia could not have left her room without being spotted by Sakuya before ToD.
• Marisa only arrived after time of death and is therefore cleared. This would only leave Flandre without an alibi, and the "vampire puppeteering" Marisa proposed would make her capable of pulling off the locked-room trick. Which basically solved Problems 1, 2 and 4, leaving me to draw a blank on 3.

Now, as to why the actual solution sucks:

1. Dictating from off-screen that no Youkai abilities were used is kind of ruining the fun, especially when you have a characters like Sakuya.
2. The door was locked as confirmed by Sakuya. Even with both Meiling and Marisa lying, she has no reason to pretend that if it wasn't.
3. Saying all entries and exit must pass the main gate is similarly silly in a setting where everybody can fly. It also means Marisa would have passed Meiling twice, with one time being just after her interview with Aya.
4. If this happened as outlined in the spoilers above, the culprit's "plan" was highly dependent on luck, e.g. waiting out Meiling to pass her.
5. There's literally no reason for Marisa to return to the scene of the murder. You could argue she forgot to erase her fingerprints from the book, but then why are Patchy's also missing?
6. It additionally hinges on Meiling acting completely out of character to help hide the truth which imho skirts dangerously close to violating both facts ① and ④.
7. Did the mangaka forgot about Koakuma?
8. Gratuitous ass- and pantyshots

Also, the book is very clearly labelled عكاشة, which means Ukasha, a figure from islamic myth. (Why a vedic concept like Akasha would be written in Arabic in the first place is anybody's guess). To be fair I think it is sometimes romanized as Akasha (like with the Nebi Akasha Mosque in Jerusalem). Not sure if this problem lies with the TL or the original though.