Sakasa zuri

Sakasa zuri (逆さ吊り, さかさづり) is an ordinary Japanese expression for hanging upside down; Jisho.org glosses it that way. Shibari Study’s glossary defines sakasa zuri as upside-down suspension and derives it from sakasa, upside down, and tsuri, suspension. Its glossary also lists kata ashi sakasa zuri (片足逆さ吊り), an inverted suspension from a tie on a single ankle. In English the form is usually called an inversion or inverted suspension.

What it is

In a sakasa zuri the head is lowest and the weight hangs from the lower body. Wikipedia’s article on suspension bondage says inverted suspensions are generally lifted by the ankles and compares them with wrist suspensions: ankle suspension can be kept up much longer, but being upside down remains a very hard position to sustain. The form also appears in tie families with other names; Kinbakuwiki’s gallery of hashira ties on a post, for example, includes inverted hashira tsuri.

Place in practice

Sources also describe inversion as the goal of a transition from another suspension. Kinbakuwiki, a German-language community wiki, describes the face-up aomuke zuri as a good base for transitions into sakasa tsuri. Ropejam Studio in London includes the inverted orientation in its sixth-level full-suspension course, and its seventh level, on dynamic suspension, teaches transitions into and out of inversion; the course excludes unplanned drops and uncontrolled spinning, and ends each sequence with a deliberate, controlled descent.

Variations by teacher and school

Definitions: Bob Roos of RopeMarks describes sakasa zuri as a vertical, head-down suspension. Peter Wettstein’s Shibaku glossary defines a vertical suspension with feet up and head down.
Single-leg form: Shibaku calls kata ashi sakasa zuri the one-legged version of the classic, dramatic inversion, which fits the entry Shibari Study gives for it.
From another suspension: Harukumo-Juku, an Osada-ryū school, presents face-up aomuke zuri as a base for transitions into sakasa tsuri.

How it developed

Pen, the Japanese design magazine, describes Itō Seiu as the artist credited with turning Edo-period rope restraint into an erotic art, and names one of his best-known images as Rinketsu Bijin Sakasa Tsuri no Shashin, a photograph of an inverted suspension of a woman in the last month of pregnancy. It dates his first suspension attempt with his second wife to 1920. English Wikipedia also describes an account of Itō suspending his pregnant wife Kise for a drawing imitating Yoshitoshi’s The Lonely House on Adachi Moor. The history article on Itō Seiu covers his working method.

Difficulty and risk

The teaching sources consulted place inversion late in a curriculum, Ropejam in its sixth and seventh levels, and its dangers are stated plainly. Wikipedia singles out head-first falls, which can be fatal or paralyzing even from a small height, and the authors of the 2023 Cureus case series write that inversions during full suspension add risks of falls, head injury and asphyxiation. Research on gravity inversion adds a further, non-rope finding: pressure inside the eyes roughly doubles when the body is head down. Kinbaku World lists sakasa zuri as advanced and high risk and describes it for understanding only.