Yggdrasil

Lore & Background

In the cosmology Yamazaki builds, Yggdrasil is not a monument to be visited but a fact to be lived within. The tree's roots plunge into the lowest strata of existence, its crown stretches beyond the highest heavens, and its trunk passes through every intermediate realm. The various 'worlds' that Chise, Elias, and their companions encounter — fae courts, elemental planes, the hidden geographies beneath England — are not separate universes so much as different rings of a single vast organism. The tree is what makes them adjacent rather than isolated, what allows a magus to step sideways from one into another.

This is where Yamazaki's worldbuilding earns its scholarly weight. She does not simply drop a Norse tree into a Celtic-flavored setting and call it done. Yggdrasil coexists with other mythological frameworks — the Celtic Otherworld, Hindu cosmological cycles, the layered afterlives of various traditions — and the series treats all of them as simultaneously true, overlapping layers of a single reality. The tree does not compete with the Celtic world; it is the trunk through which that world's branches grow. This syncretic approach means Yggdrasil is never the sole cosmological anchor, but it is the most structurally central one, the load-bearing element around which the other mythological systems are arranged.

For the characters, the tree is as mundane and as awe-inspiring as the sea. Elias speaks of it the way a cartographer speaks of the coordinate grid: without it, the map has no reference points. Chise, whose own existence is a tangle of multiple lives and multiple worlds, is perhaps the character most intimately shaped by the tree's architecture, her story literally unfolding across the branches and roots it provides.

In Their Own Story

The rain had not stopped for three days when Elias set the teacups down and said, without preamble, 'We are going to walk the roots tonight.' Chise looked up from her book. Outside the window, the Yorkshire moor was a smear of grey and green, ordinary and wet. 'The roots,' she repeated. He nodded, already pulling on his coat. 'Not the trunk. The roots. Lower than the lower world. You will see what I mean when I say the tree is not a place.' She followed him out into the rain, and the moor did not change, and then it did — the grass bent not with wind but with something beneath it, something vast and slow turning in the dark, and the ground hummed a note so low she felt it in her teeth rather than heard it. Elias walked as if he had done this a thousand times. He had, she suspected. The tree did not care that she was new to it. The tree had been there before she was born, before the moor, before the rain. It would be there after. She only had to keep walking.

Reader's Guide

If you asked Elias how the world is held together, he would likely pour you a cup of tea first and then say something deceptively simple: 'There is a tree. It is older than the names we give it.' He would explain that the realms are not separate rooms but rooms in a single house, and the tree is the load-bearing wall. The Norse tradition names it Yggdrasil; the Celtic tradition knows its branches as the paths to the Otherworld; the Hindu tradition recognizes the same structure in the Ashvattha. Yamazaki treats all of these as the same truth seen from different angles, and in her world, that is not a metaphor. It is architecture.

The consequences are practical. Every journey Chise takes — into a fae court, across a plane of elemental fire, down into the roots where time pools and thickens — is a journey along the tree's structure. The tree's stability is the reason those journeys are possible. When the tree is stressed, the realms bleed into one another, and the world grows strange in ways that hurt. The characters do not 'fix' the tree so much as tend to it, the way one tends a garden that is also a continent.

Why it still matters: because every new realm Chise steps into, every new layer of her own history that peels back, is another branch she has not yet walked. The tree is not a finished map. It is growing. And in a world where the past, present, and other-worlds are all simultaneously real, the tree is the reason 'simultaneously' is a word that means something instead of just a fancy adjective.

Did You Know?

• Yamazaki's cosmology does not privilege one mythological tradition over another; Yggdrasil coexists as a structural element alongside Celtic, Hindu, and other mythological frameworks, all treated as simultaneously litera
• The tree functions less as a destination characters visit and more as the underlying architecture that makes inter-realm travel possible at all — closer to a law of physics than a location on a map.
• The series' visual and narrative tone treats mythological elements with the same matter-of-factness as weather or geography; Yggdrasil is referenced the way a character might reference the tides.
• Chise's multi-layered identity — her multiple past lives and connections to different realms — is structurally bound to the tree's architecture, making her story a journey along its branches in a very literal sense.