Shell small for genus (to 125.8 mm SL; average adult 103.8 mm SL, n - 16), slender fusiform with long, slender neck. Protoconch small, glossy, of 1.5 to two whorls, no varix at commencement of teleoconch. Early whorls with three strong spiral cords crossing rounded axial ribs; cords increasing in number to nine or ten between sutures on penultimate whorl, varying in strength, with faint minor cords present in places in troughs between majors. Very numerous axial growth lines present overall between but not on spiral cords, giving reticulate appearance. Neck long, straight or slightly recurved in lower third, with closely-spaced spiral cords on outer surface. Body whorl rounded, occasionally with slight carination at shoulder, always at around upper third of whorl; occasional slight pronunciation of cord at shoulder as it crosses axial ribs, but no knobs formed. Axial ribs broad, gently undulating, around ten in number on body whorl. Aperture almond-shaped, slightly pinched at terminus of suture; outer lip slightly ventricose in some specimens. Labral wall corrugated, corresponding to external spiral sculpture, corrugations terminating in oblique cuts, but no developed dentition. Parietal shield developed in adults with margin detached in lower two thirds of aperture; in some specimens, columellar margin of canal also developed and detached over upper two thirds of canal. Canal open, roughly parallel-sided.
Shell pure white to off-white overall, with only very occasional rusty brown staining to crests of axial ribs on early whorls.
Periostracum moderately thick, pale brown, with finely-spaced axial lamellae bearing numerous erect, slightly opisthocline triangular thorns; periostracum occasionally thinner or absent below suture line on body whorl. Operculum typical fusinine; brown, chitinous, with nucleus at pointed and slightly reflected terminus.
Egg capsule thin, translucent, leaf-shaped with recurved collar at distal end and double marginal flange on both sides. Attached via flexible stalk roughly !4 of overall length, with slightly broadened root. Length approximately 15 mm.

Fusinus crassiplicatus is a fairly distinctive species that can be recognized by its relatively small adult size, slender shell and lack of pronounced shoulder. Its axial sculpture persists throughout adult growth. The labral wall of the aperture is clearly corrugated, in contrast to several other species examined here in which internal and external spiral cords develop independently. Large specimens can resemble F marisinicus (see below), but the latter species is thicker and heavier, has fewer, more rounded axial ribs and does not develop a ventricose aperture profile even in large adult specimens.

Fusinus crassiplicatus is known from the Pacific coast of western Japan from Sagami Bay westwards to Tosa Bay in southern Shikoku. The name was used by Thach (2005: 150) for material from Vietnam, but there was no figure and his description was inadequate to confirm this species.