The Type 97 designation was given to this gun as it was accepted in the year 2597 of the Japanese calendar (1937).

[3] Japanese 90mm, 120mm, and 150mm mortars were labeled as "trench mortars" and were effectively controlled by Imperial Japanese Army artillery units instead of infantry units.

[4] Initially Japanese trench mortars where primarily developed as chemical-delivery weapons, but would mainly see service in conventional roles during the Greater East Asia War.

This weight saving was created largely by the elimination of the Type 94's recoil mechanism, which weighed 110 lb (50 kg).

[7] Certain compromises in material and workmanship were made in the manufacture of the Type 97.