[1] Soon after introduction of the Type 97 hand grenade to front line troops, a number of problems arose.

Instability and inaccuracy of the fuse mechanism made the Type 97 almost as much of a menace to the thrower as to the recipient.

In 1939, the Army Technical Bureau developed an improved version intended to remove these flaws.

[citation needed] Operation required first removing the safety pin by pulling the cord to which it was attached and then striking the head of the fuse on a hard object, such as a rock or combat helmet, and throwing immediately.

[2] The Type 99 could also be used as a booby trap by removing the safety pin and setting under a floorboard or chair.