Body depth greater than head length, the depth contained 2.0 to 2.4 times in standard length (for fish 13 to 29 cm standard length); body width contained 2.3 to 2.6 times in the depth; caudal-peduncle depth equal to or greater than its length. Head length contained 2.3 to 2.5 times in standard length; dorsal head profile straight or slightly concave to above eye, the nape markedly convex; interorbital area flat; preopercle rounded, finely serrate, the ventral serrae slightly enlarged, the lower edge irregular but hidden by skin; subopercle and interopercle finely serrate; upper edge of operculum distinctly convex; maxilla naked, reaching vertical at rear edge of eye; a prominent knob on the ventral rear corner. Gill rakers 8 or 9 on upper limb, 16 or 17 on lower limb. Dorsal fin with IX spines and 14 rays, the membranes distinctly times in head length; pectoral-fin rays 18 or 19; pelvic fins reach to or beyond anus, their length contained indented between the spines; anal fin with III spines and 9 rays; pectoral-fin length contained 1.6 to 1.8 1.7 to 2.0 times in head length; caudal fin rounded. Lateral line noticeably arched over pectoral fin. Body scales ctenoid, without auxiliaries; lateral-line scales 60 to 65; lateral-scale series 101 to 117.
Colour: Head, body, and fins reddish orange: 7 lemon yellow bars on dorsal part of body, extending onto dorsal fin; 3 broad yellow bands radiating from eye: fins red, except for extension of yellow bars from body into dorsal fin and membranes at tips of dorsal-fin spines, which are orange. Juveniles more yellowish, with a large black spot in dorsal fin, pelvic fins and tips of interspinous dorsal-fin membranes blackish: tips of pelvic fins blackish in large juveniles or small adults.

Tropical western Pacific: southern Japan, Taiwan, Guam, Philippines, South China Sea, Samoa, and Tahiti.

C. igarashiensis is a rare, deep-water grouper; Schroeder (1980) gives the depth range as “down to 80 m,” and the specimen from Tahiti was taken in 250 m. Like most groupers, it is said to feed on fishes and crustaceans (Schroeder, 1980).

Maximum total length about 43 cm.

This distinctive species differs from all other species of Cephalopholis in its greater body depth and unique colour pattern. The species name is an adjectival patronym in honour of Mr Igarashi, who collected the holotype.