Text and picture copied from "Japanese Infantry Weapons" cincpac cincpoa Bulletin 55-45, 15 March 1945 :

"The experimental Incendiary Hand grenade is 13.5 inches long, has a diameter of 2.2 inches, and weighs approximately 1-3/4 lbs. It consists of a body, handle, and fuse.
The grenade body is a steel cylinder which contains a bursting charge of 1 3/4 ounces of black powder and an incendiary compound composed of 13 ounces of small pieces of phosphorus impregnated rubber, carbon disulfide, and crude oil.
A wooden handle is attached to the base of the body. At the other end is a fuse of the usual 10th Year type found on other Japanese grenades".