The woman astride, the standard chausu (tea-mortar) configuration. Then a variation: one of the knees lifts from the bedding, with the leg held in air and the body supported on a single knee. The Edo-period artists, looking at this variant, named it uki-chausu — “floating mortar” — the uki- (“floating”) prefix marking the lifted-leg variation of the parent chausu configuration. The forty-eight hands tradition’s systematic operation of variation-by-prefix on its parent position-names is exemplified directly in this configuration.

Overview

Uki-chausu (Japanese: 浮き茶臼, uki-chausu; also 浮茶臼 in compact form; literally “floating mortar”; English working translation: floating-chausu, one-knee variant of chausu, one-leg-raised cowgirl) is a forty-eight hands variant of the chausu (tea-mortar, face-to-face cowgirl) position. The variant retains the parent chausu configuration’s face-to-face cowgirl-style coupling but adjusts the receiving partner’s leg-position: one knee remains on the bedding (or on the inserting partner’s side), while the other leg lifts from the floor. The configuration trades the parent position’s stability (both knees as anchor-points) for increased range of motion and angle-variability (single-knee anchor with the lifted leg’s positioning adjustable).

The position is one of the more directly-named variants in the forty-eight hands catalogue, with the uki- (“floating”) prefix functioning as a recognised modification-marker that operates across multiple parent positions. Uki-matsuba (a related variant of matsubakuzushi with similar leg-lift modification), uki-fune (a side-position variant with similar modification), and uki-chausu together compose a sub-family within the forty-eight-hands catalogue where the uki- prefix marks the systematic lift-one-element variation of the parent position.

Etymology

Chausu (茶臼) names the classical Japanese tea-grinding mortar, the stone hand-mill used to grind tea-leaf into the powdered form used in tea-ceremony preparation. The motion of grinding involves a rotational hand-action on the upper mortar-stone against the lower mortar-stone, producing a steady rotational-and-pressing motion. The Edo-period forty-eight hands tradition borrowed chausu as the position-name for the face-to-face cowgirl configuration, with the woman’s circular-and-pressing hip motion atop the man’s body evoking the tea-mortar’s grinding motion. The name is one of the most-recognised forty-eight-hands position-names and the parent configuration is one of the central positions in the catalogue.

Uki (浮き) is the nominal form of uku (“to float”, “to rise”), applied as a prefix to forty-eight-hands position-names with the meaning “lifted-from-floor variant of the parent position”. The pattern operates systematically across the catalogue: where a parent position has the receiving partner’s body fully supported on the floor, the uki- variant lifts one body-part from the floor in a recognised geometric variation.

Uki-chausu thus reads as “the chausu with one element lifted” — specifically, with one of the receiving partner’s knees lifted from the floor. The decorative-aesthetic dimension of the uki- prefix is part of its operation: the lifted element introduces visual-and-geometric variation that the parent position’s stable configuration lacks, with the resulting variant carrying a more decorative-aesthetic register.

The position-name appears in the late-Edo-period erotic-print catalogues including Makurabunko and Endō Nichiya Nyohōki (early-to-mid nineteenth century). The exact dating of the variant’s first attestation is unclear; the configuration likely emerged in the elaboration of the parent chausu position during the mid-to-late Edo period, with the uki- prefix consolidating as a recognised variation-marker over the same period.

Configuration and execution

The base configuration starts from chausu: the inserting partner lies supine; the receiving partner straddles the inserting partner facing him, with both knees on the bedding (or on the inserting partner’s sides), with the receiving partner’s pelvis lowered to the inserting partner’s pelvis for coupling. The receiving partner controls the rotational-and-pressing hip motion that defines the parent position.

Uki-chausu modifies the base configuration: the receiving partner lifts one leg from the bedding while keeping the other knee in contact with the bedding-or-the-inserting-partner’s-side. The lifted leg may be held at various heights: at the moderate variant, the leg is lifted just clear of the bedding with the receiving partner balancing on one knee; at the full variant, the leg is extended outward toward horizontal, with the receiving partner’s pelvis substantially-tilted by the asymmetric configuration.

The lifted-leg position changes the configuration’s geometric properties substantially. The receiving partner’s pelvis can no longer rotate symmetrically; instead, the pelvis adopts an asymmetric configuration that changes the angle of coupling continuously as the receiving partner moves the lifted leg. The motion-range of the coupling is consequently increased, but the stability is reduced: the single-knee anchor offers less support than the two-knee parent configuration.

The configuration’s practical execution requires the receiving partner to balance on the single-knee anchor while controlling the lifted-leg position and the coupling motion. The inserting partner typically supports the receiving partner with both hands at the waist or hips, contributing to stability while the receiving partner manages the asymmetric configuration. Edo-period shunga depictions show the configuration in various degrees of leg-lift, with the more dramatic variants emphasising the lifted-leg’s decorative line as a compositional element.

Classical sources

In Edo-period shunga, uki-chausu appears in the cowgirl-position sub-section of the broader forty-eight-hands repertoire. The standard depiction places the receiving partner astride the inserting partner with one leg lifted, the lifted leg’s line operating as a strong compositional element extending upward or laterally from the central body-mass. The composition is typically organised around the lifted-leg’s diagonal-line as the principal visual feature, with the coupling-pelvis at the composition’s centre.

The Utamaro-lineage shunga prints emphasise the lifted-leg’s decorative-aesthetic potential, with the leg drawn in flowing-extended lines and the foot-and-toe details carefully rendered as the visual focal point. The Hokusai-lineage prints work the configuration more geometrically, with the lifted-leg-and-inserting-partner’s-body forming geometric line-compositions that the picture-plane organises around.

The text-captions on Edo-period prints depicting uki-chausu sometimes deploy phrases like “with one leg lifted, as if dancing” (片足を浮かせて舞ふごとし) or “the chausu floating and freer” (茶臼を浮かしてさらに自在なり). The captions both name the variant and indicate the configuration’s specific-feature reading: the variant gives the standard chausu a “freer”, “more skilful” register, with the receiving partner’s lifted-leg-control marking technical and aesthetic accomplishment.

Variants and adjacent positions

Chausu (tea-mortar / face-to-face cowgirl): the parent position, with both knees on the bedding.

Uki-chausu: the one-leg-lifted variant (the present position).

Rear-mounted cowgirl (haimen kijōi): the back-to-front cowgirl variant, with the receiving partner facing away from the inserting partner. Distinct from uki-chausu in that the orientation differs, not the leg-position.

Face-sitting (kao-nose / ganmen-kijōi): the configuration of the receiving partner straddling the inserting partner’s face. A different sub-category of the cowgirl-family.

Woman-on-top (kijōi): the contemporary umbrella term for cowgirl-style positions, of which chausu and uki-chausu are historical sub-variants.

Standing cowgirl variants: with the parent configuration adapted to standing-position contexts. Less common in classical depiction but appearing in modern adult-content production.

The distinguishing geometric feature of uki-chausu in this cluster is the single-knee-anchor configuration with one leg in air. The configuration’s specific signature of receiver-led variation with asymmetric pelvic configuration differentiates it from the symmetric parent chausu and from the other cowgirl-family variants.

Reception psychology

The configuration’s psychological register continues and extends the parent chausu position’s emphasis on receiving-partner-led motion. In the parent chausu, the receiving partner controls the rotational-and-pressing hip motion that drives the coupling. In uki-chausu, the receiving partner additionally controls the lifted-leg’s position, giving the receiving partner a wider range of expressive variation in the coupling motion. The configuration’s distribution of agency tilts even further toward the receiving partner than the parent chausu, with the inserting partner in a relatively-passive receiving role.

The Edo-period commentary on the configuration includes phrases like “continuously changing the angle, never wearying” (角を絶えず変じて飽きさせず), reflecting the recognition that the asymmetric leg-position introduces continuous variation in the coupling angle that the symmetric parent position cannot match. The configuration’s reception in the period seems to have emphasised this continuous-variation register as a recognised aesthetic-feature.

The configuration’s practical difficulty — balance management on single-knee anchor with the lifted-leg’s position-control — gave the position a register of receiver’s skilful execution. In a tradition that gave the receiver-led cowgirl-family positions substantial weight relative to inserter-led positions, the uki-chausu variant operated as a particularly-receiver-emphasising configuration, with the receiver’s technical and physical accomplishment as a recognised dimension of its execution.

Modern reception

In contemporary Japanese adult-content production, the classical name uki-chausu is rarely used. Modern vocabulary deploys kata-hiza kijōi (“one-knee cowgirl”), tate-hiza kijōi (“standing-knee cowgirl”), or contextual descriptive vocabulary instead. The classical name survives primarily in scholarly literature on the forty-eight-hands tradition, in period-set or classical-vocabulary-themed productions that explicitly invoke the forty-eight-hands catalogue, and in tradition-revival contexts.

The configuration itself remains a recognised cowgirl-position variant in contemporary practice, with the contemporary vocabulary covering the same geometric configuration that the classical uki-chausu named. The cultural-vocabulary discontinuity is in the name rather than in the configuration; the configuration is alive and well in contemporary production, even where the classical name has substantially fallen out of use.

Cultural reception

The uki-chausu name and the broader uki- family of forty-eight-hands variants illustrate the systematic-elaboration dimension of the Edo-period erotic-print tradition’s position-vocabulary. The tradition was not a static catalogue of fixed entries; it was an open elaboration-system that generated new position-names by applying systematic prefixes (uki-, tate- “standing”, yoko- “sideways”) to parent positions and producing recognised variants. The catalogue’s depth and continuing-elaboration is part of what gives it its cultural-historical interest.

The position-name’s continued availability in scholarly literature gives it a small but stable cultural-historical presence. As a worked example of the forty-eight-hands tradition’s systematic-elaboration operation, the uki-chausu and the broader uki- family of variants give cultural-historical scholarship a window into how the Edo-period tradition organised its position-vocabulary in a regular, generative fashion — not as a fixed list, but as a productive system that generated its catalogue through systematic operations on its parent positions.

The cowgirl-family’s particular position in the Edo-period tradition — as the position-family that most prominently acknowledged receiving-partner-led motion and control — gives the uki-chausu variant a continuing cultural-historical interest. In a cultural-historical period not generally noted for its acknowledgment of female sexual-agency, the cowgirl-family’s central position in the forty-eight-hands catalogue (with the parent chausu among the most-prominent positions in the catalogue) suggests a more complex picture, with the shunga and forty-eight-hands tradition preserving a recognised receiver-led position-family that contemporary scholarship continues to examine for what it reveals about Edo-period sexual culture.

Related Terms

• Chausu (tea-mortar, parent position)
• Woman-on-top (kijōi, contemporary umbrella term)
• Rear-mounted cowgirl (haimen-kijōi)
• Face-sitting (kao-nose)
• Forty-eight hands
• Shunga