Thanks for the fast reply, Kips McKipzerson!
Please bear in my mind that this dream is pretty bizarre, so you shouldn't take it seriously at all. Also, I have a tendency of not remembering very well what my dreams are, so things may not be accurate.
So the game is released, and there's a English strategy guide for it as well.
The first boss (I think it's the first boss) is a girl with long blue hair dressed in a white (can't remember what kind of clothing), and she sits in a bucket like Kisume. She also came out from a well if I remember correctly... According to the guide, she's based off Sadako Yamamura from The Ring, I think. The guide only mentioned The Ring, not the name, but I know for sure that it was referring to Sadako.
Another boss is a girl with whitish-blue hair and somewhat pale skin. She wears a white sleeveless shirt that shows her midriff and and a white skirt if I remember correctly, and she bears a bit of resemblance to Shinki. It turns out that she is a robot that is supposed to be modeled after her.
Okay, this is where the dream becomes stranger... Sara and Yumeko are back! However, the former isn't really Sara herself. The guide says that's an alternate dimension of her, whatever that means... She has a different name, but I can't remember what it is, and also, she's the person who built that Shinki-lookalike robot. Yumeko, strangely enough, is called Yumarth (at least that's what I remember), and I remember that there was no mention at all if she is the same Yumeko or not.
And now, this is probably going to drive some people crazy... I remember laughing in an overdramatic manner when I saw this. So... Mima is back... and as the extra stage's boss! However, she's been drastically redesigned. She now has red hair and her clothes consists of mostly yellow and red if I remember correctly... I can't remember the details, not even what kind of hat she's wearing, but it might be the same one, just with a different color... However, the guide says that she is the same person, and it also says that she is looking for inner peace, I think...
Okay, strange dream... While I am in no way a fan of horror movies, stories, and such (though I do play Castlevania), having a character based of Sadako would actually be... interesting...