This are theories for the Touhou Project CD stories and characters. For the rest of the franchise, see here.
Dolls in Pseudo Paradise
- The 4th: I belive the fourth and the girl of the group is Alice. I reread a lot of stuff and decided to drop my guess that she was Maribel. There are some nods elsewhere in the canon that points to Alice. Then if so then this could be her new retconned backstory on how she became a Youkai in the first place. I also think that the girl on the cover is Alice, or rather to be more specific, the true Alice (a.k.a. Ex-Alice). Remember the locked grimoire? Yea, if unlocked could result in the release of Alice's full potential. Also, the cross she is seen holding, I don't think it is a regular christian cross but rather a marionette control rod. And another thing, if her old backstory is still canon, then perhaps she was put outside Gensokyou by Shinki maybe to keep her away from magic, with perhaps a dose of amnesia to make sure she doesn't chase it. Then if she already had massive magical knowledge and power when coming into contact with Gensokyou again she would have most likely transformed to a Youkai right away like in the story. One final thing, during the last part she is mentioned to have hanged herself, however all that is stated is that her feet never reached the ground this time. That could imply that ether she started to float or that the rope simply couldn't kill her due to now being a Youkai. Additionally, the whole story is one huge reference to Agatha Christie and Alice's last name likewise takes inspiration from her.
- The Clown: I think the clown is most likely a doll (possibly sentient). This one is of course something I link to the True Alice mentioned above, perhaps born at the same time she her self was reborn. If it is a doll then of course it would tie into her doll theme and the reason I think it is sentient is that it seemed to act on it's own without her direct input. And if so that would suggest a rather sadistic personality, or at the very least extremely overprotective of it's owner. Also the reason I think it is linked to her is that the 4th was the only one who never once encountered it. As for appearance I guess it has some traits similar to the 4th and is female (should seem kinda obvious since this is Touhou) based on the fact that one of the honest men found it beautiful and seemingly fell in love with it or something, so unless he was gay then that is the most likely conclusion.
- The Title: This one should be the easiest to understand. The Pseudo Paradise part simple refers to Gensokyou but as a Crapsaccharine World. The dolls part however most likely refers to the honest men suggesting that they where either strung along all the time by some single puppet master or if they where flat out People Puppets.
Maribel & Renko
- Renko and Maribel, obviously. Reimu isn't all that interested in how the world works, so long as it isn't bothering her.
Renko's ability to determine her location and the current time from the moon and stars could actually be highly advanced mathematics, but she just hasn't figured it out yet; this would also give an excuse for her power not growing stronger: it has, but she's unable to use the full extent of it until she realises that it's actually the ability to perform complex calculations in her head at high speeds. She already has her own ability, putting her on a level above normal humans; if she was to be turned into a youkai, this would likely translate over as increased magical powers, possibly enough to summon her own shikigami. It could be argued that Chen was someone she met after Maribel was Trapped in the Past, who passed on at some point; she then summoned her friend's spirit as a shikigami like Maribel!Yukari did for her.
However, what if, they were humans from the past? Their world was so technologically advanced that every mystery of the world has been solved, and even the supernatural can be explained by science. Because they have known everything, the humans forgot their fear and became arrogant and careless. Through this, an Apocalypse How ranging from Class 3 to Class 5 happened, destroying their civilization.
There were survivors, however. These survivors, horrified of the apocalypse, seeks a pure land freed from death and impurity: The Moon. They traveled to the moon and built a pure, deathless civilization there. We know them as the Lunarians. Among these was Eirin Yagokoro.
The apocalypse didn't end all life, however. Some species survived, and continued to live and evolve, effectvely resetting the world. Humans once again rise to sapience and started civilization again.
The Lunarians weren't the only survivors. There were other group of people that refused to go to the moon, and instead stayed on Earth. Knowing that the lack of fear of the unknown was what brought the old world's destruction, they turned themselves into the 'unknowns' themselves, and kept the humans from finding out the secrets of the 'unknown'. They were then called gods, demons, monsters, youkai, etc.
Yet, human civilization keeps advancing. Realizing humans would soon know of the 'unknowns' at that rate, one of them, erected a barrier to keep the unknowns as unknowns. The land inside the barrier, where humans keep fearing the unknown, is acting as a failsafe in case that the humans outside repeat the mistake and destroyed the world again. The one who came up with this was Maribel Hearn, now adopting the name of Yukari Yakumo.
- Considering that Lafcadio Hearn, an influence on Maribel's surname, has Koizumi Yakumo as his Japanese name, this may actually hold water.
First, it puts it in a reasonable timeframe where Sumireko could be Renko's grandmother.
And secondly and more importantly, it is right after another cycle in the Sexagenary cycle. So perhaps at 2065 something extremely major happened that lead to countless deaths and made the world where they live into what it is. Perhaps it is some time after the event and the world has started to slowly recover from it.
- Or she was a single parent, for any number of reasons. With no husband to erase her family name, Sumireko simply raised her children as Usamis. Any son would have the capacity to carry the name forward into Renko's generation.
- Alternatively, Renko could be a kitsune's descendant (and by extension, Sumireko) as Abe no Seimei (an onmyoudo, and by extension, an astrologist) was, in legend, the child of a kitsune as well. Not to mention she probably retains some of a kitsune's (and using the computer allegory, a shikigami's) affinity for math.