The B6N2 mod. 12 Ko, designated as Tenzan 12A (天山一二型甲), was a minor variant of the standard Tenzan 12 that replaced the two Type 92 (7.7 mm) LMGs with the German-inspired 13 mm Type 2 and 7.92 mm Type 1 guns, derived from the MG 131 and MG 15 respectively. It also had an H-6 (Type 3 Ku 6 Mod.4) air-to-surface naval Yagi-antenna radar mounted on the wing leading edges and on the sides of the rear fuselage.

It was introduced in Update "Starfighters". The Tenzan 12A's improved armaments and overall agility of the Tenzan 12 can catch any pursuing aircraft off guard, as it can out-turn most of them and hit them with lethal firepower. The main role remains to be a torpedo-/level bomber, carrying either a single large bomb/torpedo, 2 x 250 kg bombs, or a rack of 6 x 60 kg. The enhanced rear firepower can be used to lure in unsuspecting fighters that might underestimate a torpedo-bomber without forward firepower.