Maria Holic/WMG

Mariaâ€ Holic takes place in the same universe as Girls Bravo.
Kanako exists to karmically balance out Yukinari, who breaks out in hives at the touch of a girl.

Mariya and Shizu are Light and Misa's children.
Whether or not alcohol was involved in their conception; Misa gave birth to them shortly before  They were adopted into a fancy (and eccentric) family. Interestingly, Ryuk did try to offer Mariya the Death Note, but playing mind games with Schoolgirl Lesbians is more entertaining.

Mariya is secretly Tsundere for Kanako.
Think about it. It's possible.

Kanako's back story is actually a Stealth Parody of Rape and Switch
Seriously, a girl turning lesbian from having her bloomers and recorder stolen by boys is too over-the-top to be taken seriously. Kanako would have turned out lesbian no matter what, she's just too Genre Blind for her own good and uses this as an excuse. Plus Rape and Switch / Does Not Like Men shows up used straight in a lot of Girls Love series, and since this is a Deconstructive Parody of one....

Kanako was a lecherous (male) pervert in life
Kanako seems to be one of those classic 'male pervert' types in anime transplanted into a female body at an all-girls school. She was a male pervert character, then she died (and as a result, lost her memory.) She is currently being karmically processed, which is why she's subject to such abuse, and also why she is surrounded by irony. However, she has yet to give up all her voyeuristic habits, such as. This also explains the apparent supernatural elements and the medium awareness.