Akasegawa and his collaborators developed a typology over years of collective fieldwork, published in full in the Thomasson Illustrated Encyclopedia (トマソン大図鑑). The categories used in this archive are adapted from that system — consolidated where the original types blur together, and renamed where the original Japanese required cultural context to read.

Pure Staircase

A staircase that goes up and comes back down with nothing at the top — no door, no entrance, no purpose. Usually there was once a door. The handrail is often still maintained. The original Thomasson, discovered by Akasegawa in Yotsuya in 1972.

Useless Door

A door that cannot be used — blocked with concrete, sealed behind a later wall, or opening onto empty air. It retains the full dignity of a door. In some cases it stands alone, with no wall around it at all.

Useless Window

A window that has been filled in or made permanently inaccessible, but whose frame or outline remains. The care taken in blocking it is often what makes it a Thomasson rather than simple renovation.

Orphaned Eaves

A roof overhang or canopy with nothing beneath it to protect — the window or door it once sheltered has been removed or sealed. It continues to offer shelter to an absence. Called hisashi in the original typology.

Ghost Wall

The two-dimensional impression of a demolished building left on the surviving wall of its neighbour — rooflines, floor levels, staircase angles, chimney shadows. A record of something that no longer exists, preserved in the surface of something that does. Called the A-bomb type in the original typology.

Elevated Type

A normal object — a door, a handle, a switch, a sign — stranded at an abnormal height, unreachable without equipment that is no longer there. Usually the result of a staircase, platform, or mezzanine being removed. The object itself is intact. Its context has vanished.

Sealed Surface

A wall where something has been filled in — but the filling is legible. A doorknob still protrudes. A window frame is visible beneath plaster. A tap emerges from concrete. The original opening is gone; its ghost remains in relief.

Swallowed Object

A structure being consumed by its surroundings — a post embedded in poured concrete, a fence absorbed into a growing tree, a sign half-buried in accumulated ground. The city or the natural world has grown around it without removing it.

Roadside Remnant

A post, stump, bollard, or object whose original function is no longer apparent — maintained or simply left, attached to a surface, serving nothing. Includes the severed stumps of removed telephone poles, called the Abe Sada type in the original typology.

Broken Sign

A sign from which letters, symbols, or meaning have been lost — through weathering, vandalism, or removal — leaving something that still presents itself as a sign while communicating nothing. Called Uyama in the original typology, after the first example found.

Uncategorized Thomasson

A Thomasson that does not fit the existing types, or whose type is unclear. Akasegawa expected the taxonomy to be incomplete. Submit what you find.