Stroke the sole and press the centre, and the finger sinks deep. This is the region that does not touch the ground, the tsuchifumazu (literally “where one does not tread the earth”). It is an anatomical structure for distributing body weight in walking and standing, and one of the parts of the body furthest from the genitals. Yet it holds a strong, independent place at the core of foot-fetish preference. That very distance from the genitals makes the arch the symbolic site of a paraphilic preference.

Tsuchifumazu is the Japanese colloquial name for the curved central region of the sole that does not touch the ground. In anatomy it is the medial longitudinal arch, the central one of the three arch structures (medial longitudinal, lateral longitudinal, and transverse), serving shock absorption and weight distribution in walking and standing. It is one of the skin regions furthest from the genitals on the body.

Anatomy

The arch structure of the sole comprises three arches: medial longitudinal, lateral longitudinal, and transverse. The arch corresponds mainly to the medial longitudinal arch, a hollow seen from the skin side of the arched skeletal structure formed by the calcaneus, talus, navicular, cuneiforms, and first metatarsal. The plantar fascia, posterior tibial tendon, and flexor hallucis longus tendon supporting the arch from below alternate tension and relaxation to realise a spring-like shock-absorbing function.

The skin here is thinner than on other regions of the sole (heel, forefoot), with a thinner keratin layer, because the arch does not contact the ground directly; skin unexposed to external stimulation retains its softness. Innervation is dense from the plantar branches of the tibial nerve, giving high sensitivity to touch, pain, and the tickle reflex.

The degree of arch development varies widely, described in three grades: flat foot (low arch), normal foot, and cavus foot (high arch). In flat feet the arch is hard to discern; in high arches a deep arch forms.

The arch as an erogenous zone

With its thin skin and high nerve density, the arch shows a degree of sensitivity as an erogenous zone. When made an object of caress in a sexual setting, light contact often triggers a strong tickle reflex, received as pleasure by some and as discomfort by others, with large individual variation.

Caress of the sole developed within therapeutic traditions not directly linked to sexuality, such as Eastern reflexology and traditional Thai massage. These are sometimes applied in sexual settings, with a flow from foreplay beginning as foot massage into full sexual activity implemented in certain sex-industry business types (massage-style establishments).

At the core of foot-fetish preference

The arch occupies a privileged place within foot fetishism (the cluster of preferences including footjob (ashikoki), high heels (heel), and stockings).

First, as a visual sign. Of the whole sole, the curve of the arch is the most aesthetically valued region. A foot with a deep arch is praised as “well-shaped”, forming the aesthetic core of foot-fetish preference. In gravure and adult photography centring on the feet, angles and lighting emphasising the shadow of the arch are chosen.

Second, the property of maximal distance from the genitals. That the arch functions as a sexual sign demonstrates the extremity of preference for the part of the body furthest from the genitals. Unlike preferences for the genitals, breasts, or buttocks directly, foot and arch fetishism is analysed in psychology as a phenomenon in which the object of sexual interest “shifts” to the body’s periphery, classically treated as a representative type of paraphilia. Havelock Ellis’s Studies in the Psychology of Sex and Freud’s writings both describe foot fetishism, positioning it as one of the most classical paraphilic types.

Third, as a sign of being trodden upon and of worship. Within foot fetishism there is a strand that receives being trodden by the sole (trampling) as sexual pleasure. The arch, as the region pressing against the body in the act of treading, becomes the medium conveying trace, pressure, and warmth. In BDSM contexts, licking a dominatrix’s foot, being trodden, and taking the toes into the mouth encode relations of domination and submission mediated by the sole.

Cultural references

Artistic representations thematising the arch are found East and West: the Buddha’s footprint (the patterns carved on the sole of the Buddha), the foot-stamping of Noh, and the footwork of Japanese dance all attend to the sole as a whole, though representation focused specifically on the arch is found mainly in modern photographic and moving-image media.

In adult content, foot-fetish specialist labels and genres exist independently, with photography centring the arch in composition standardised. On FANZA and DLsite, works tagged “soles”, “foot fetish”, and “arch” hold steady demand.

Related Terms

• Heel (kakato)
• Beautiful legs (bikyaku)
• Footjob (ashikoki)
• High heels (heel)