Ookami-san/WMG

The Narrator is a Time Lord
She traveled back in time to document the goings-ons of Otogi City. Hence the "long time ago" and "they all lived happily ever after" at the beginning and end of each episode, because they make sensefrom her point of view (the relative future).

Ryoko is Taiga
I won't state the obvious reasons. But it's either Taiga has finally grown taller, or a clone created by Majolica.
 * How about she's not Taiga, but her and Ryuuji's daughter? See this picture for the similarity.
 * Astounding resemblance. Which just makes the possibility that her parents let even more depressing.
 * While Ringo is Ami and Minori's adopted daughter. It would explain where she picked up her act.
 * Jossed in Canon! In episode eight, while they are looking for brides, Taiga actually appears as one of the potential brides in a blink-and-you'll-miss-it scene.

The Otogi Bank is run by the Corleone Family/or is another crime family
After playing the godfather 2 and watching the otogi bank in action, I have deduced that it is being run by Michael Corleone's decendants. I mean look at them! It's a f*** ing extortion racket. Plus their structure looks like a typical family (name listed as in the character sheet):
 * Ryoko Ookami - Soldati (soldier - fifth)
 * Ryoshi Morino - Soldati
 * Ringo Akai - Caporegime (captain - fourth)
 * Liszt Kiriki - Capo famiglia (Don - first)
 * Alice Kiriki - Sotto Capo (underboss - second)
 * Otsu Tsurugaya - Associate (buttonman - unranked)
 * Taro Urashima - Soldati
 * Otohime Ryugu - Soldati
 * Majolica le Fay - Consigliere (adviser - third)



The butler of the Nezumi Corporation was deliberately being rude to the girls.
Well, it looked like the whole bridal search was just to teach the young heir on how some things can't be acquired through wealth or power. The butler was only pretending to be rude so that his master wouldn't choose anyone aside from the "Zashiki-warashi".
 * The only thing that would make this more obvious is if he straight up said so. Hell, he explicitly states that what there is one thing that cannot be bought, and that can never turn bad later, is a childhood friendship.

Urashima isn't actually interested in any girl other than Otohime.

 * It seems that he not only expects her to break up any flirtation with another girl, but looks forward to it, especially considering she consistently *ahem* "extracts his essences." The one time she doesn't show up he looks around pretty expectantly for her. He probably just thinks jealousy is cute.
 * Or he's a man who knows how to get what he wants.
 * Or maybe Urashima acting like lecherously/jealousy thing is a signal that they "get some" and the whole thing is an act for everyone else.