WMG / Ni no Kuni

Lucien cast Ashes of Resurrection on the Sage's Daughter.
The Kingdom of Halcyon did eventually find her; and killed her. Seeing her as his sole light; he learned the forbidden spell and resolved to cast it, no matter the cost. As revealed by the story "The Bear-Man and the Princess's Tears" in the Wizard's Companion; the Equivalent Exchange is forgetting that the resurrected person exists; so Lucien erased his Morality Chain from his mind. This made his despair even greater as he can't remember anything good coming from his disobeying Halcyon; making his becoming Shadar all the more quick. Naturally, when he died, the memory erase no longer applied.

Oliver will not cast Ashes of Resurrection on his mother because he knows the price and won't pay it.
He has the Wizard's Companion, after all, and has read all the stories; including "The Bear-Man and the Princess's Tears." You have to be utterly committed to be able to cast the spell; and that's too high a cost.

The Fairy Godmother was Alicia's Soul Mate.
By permanently going back in time and not returning, Alicia condemned her Soul-Mate(s) to the same limbo that Shadar committed his; (except the one saved by Alicia). However, as shown by the Conductor; "lost" Soul-Mates can get out of limbo; but they aren't quite human anymore. Because this Alicia was taking up her space in Oliver's world; Alicia's soul-mate instead manifested in the world without an Alicia; the Other world that Alicia had left as a spirit being like the Conductor.
  • This is why the Fairies don't have Soul-Mates like everyone else; they're created from an Orphaned Soul.
    • Super Irony: Oliver got "rebirthed" via the Fairy Godmother too.

The Setting (both worlds) was created at the end of MOTHER 3.
Because two different agencies were trying to free the Dragon and imprint upon it; while Good triumphed, this still lead to two worlds being created. Both worlds turned out Bright (Ghibli Earth is friendlier than our Earth, but due to Emptiness from the Masked Man, it has no magic), but as always, Free Will leads to exceptions.
  • The Dragon became the Guardians of the Worlds.

The voice who yells, "Nice!", "Now's your chance!", and "Supercharged!" in battles is Oliver's mother's voice.

Howl is Marcassin's Soul Mate.
  • Marcassin is already identical to Howl and there are many similarities between the two, like how both are powerful mages and seem very vain and Wangsty at first glance. Well if you combine the Ghibli film's character design for Howl and remember that the book mentions that Howl originally came from our world and if we assume that the town Oliver comes from is supposed to be our world the only problem would be the time period differences.

The whole thing was staged for Oliver's "benefit".note 
  • Shizaku/Drippy is some omnipotent being who set the whole thing up in order to teach Oliver a(n unfair) moral lesson: that his mother is gone, and needs to accept it. However, as many people can tell you, "gone/dead" and "accept" are subjective terms. In fact:

The entire game is a metaphor for the "Five Stages of Grief" theory.note 

The Zodiarch Council are from a third world.
  • At the end of the game, the Zodiarch Council is revealed to be Dead All Along, and the council that we've seen (well, 11 out of 12) are just hardlight illusions made by The White Witch to stave off her isolation. Yet somehow they manage to come back to life as hideous monstrosities that seek to kill Oliver, The White Witch, and take over Ni No Kuni. The White Witch theorizes that her magic has spun out of control and created them against her will, but what if they were always something more? There's more than two worlds, and harvesting the resources of this lush, magic-saturated, war-free world would be more than enough reason to open up an expensive portal between two entirely alien worlds and masquerade as an insane demon queen's illusion puppets, harvesting resources while hidden away by her madness. Not to mention, the Miasma cataclysm would be a good catalyst for a portal.