Yonaguni — one of the smallest horse breeds in the world, classified as a true island pony. Extremely primitive, compact and sturdy horse of brachymorphic (short and wide) conformation, with well-developed musculature and strong bone structure. Height at withers 1050–1220 mm (average 1120–1150 mm), live weight 180000–240000 g (usually 200000–220000 g), body length 1300–1450 mm. Format index (body length / height at withers) ≈ 1.20–1.25. Bone index (cannon bone circumference / height at withers) ≥ 13.5 %. Head relatively large, broad in the frontal region, with a straight or slightly concave profile. Neck short, thick, with a low, almost horizontal set. Body compact, barrel-shaped, deep. Back short, broad, often slightly soft. Croup rounded, slightly sloping. Limbs very strong, with short pasterns, wide cannons (length of front cannon 140–165 mm, circumference 145–170 mm). Hooves broad, strong, rounded, often cupped, with black or dark horn wall. Tail low-set, thick, with coarse hair, often reaching the ground. Winter coat very dense and long (up to 40–50 mm), with undercoat; summer coat short, smooth, shiny. Skin thick, darkly pigmented. Acceptable colors: bay (predominant), black-bay, chestnut, mouse dun, brown, roan, dun with primitive markings (dorsal stripe, zebra striping). Not allowed: pinto, spotted, cream, silver. High value is placed on the presence of primitive markings. Distinguished from other Japanese breeds by the smallest stature, pronounced “forest pony” type, high percentage of primitive markings, strong constitution and low neck set.