A letter that ties the bond between them.

A shy 11-year-old's life takes a strange turn when she discovers three hungry goblins living in the attic of her new house. She misses her old life. She misses her father so very much. Until she makes some new ghoulish friends.
In A Letter to Momo, consciousness is carried by monsters and creatures — a plane of “spirit island”. The story fights on E8/E9 of the E0–E14 reality ladder, compressing grief, family, tradition, spirits.
Films fighting at the same level of reality, about the same things.
Other films that move a human interior onto the same kind of thing.
Teen Wolf: The Movie (2023)consciousness in monsters · spirit‑possessed teen drama
How the Grinch Stole Christmas (2000)consciousness in monsters · Whoville holiday town
Hereditary (2018)consciousness in monsters · coven horror
Onward (2020)consciousness in monsters · elfic suburbia
The Grinch (2018)consciousness in monsters · holiday town
Nanny McPhee (2005)consciousness in monsters · magical Victorian householdThe same preoccupations carried by a different kind of thing — grief told through the dead, an animal, a machine.
Umma (2022)consciousness in the dead · family, grief
The Medium (2021)consciousness in the dead · family, grief
Child of Kamiari Month (2021)consciousness in animals · family, grief
Brave (2012)consciousness in animals · family, tradition
Kubo and the Two Strings (2016)consciousness in objects · family, tradition
Monster House (2006)consciousness in objects · family, grief