Guinea, the IJAAF used the aircraft in an anti-ship role, where the Ki-45 was heavily armed with one 37 mm (1.46 in) and two 20 mm cannons and could carry two 250 kg (550 lb) bombs on hard points under the wings. 1,675 Ki-45s of all versions were produced during the war. The first production type (Ko) was armed with two 12.7 mm (.50 in) Ho-103 machine gun in the nose, a single Type 97 20 mm cannon in the belly offset to the right, and a trainable 7.92 mm (.312 in) machine gun in the rear cabin; this was followed by the Otsu with the lower 20 mm cannon replaced by a 37 mm (1.46 in) type 94 tank gun, to counter B-17 Flying Fortress bombers. While the firepower was devastating, manual reloading meant that typically only two rounds could be fired on each gunnery pass. The next type (Hei) restored the 20 mm cannon, and this time placed an automatic 37 mm (1.46 in) gun in the nose. A later addition in the Tei type were twin obliquely-firing 20 mm Ho-5 cannons behind the cockpit, and often propulsive exhaust stacks. Soon after entering service, the Ki-45 was assigned to home defense, and several were dispatched against the Doolittle raid, though they did not see action. The craft's heavy armament proved to be effective against the B-29 Superfortress raids which started in June 1944. However, its performance was insufficient to counter B-29s flying at 10,000 m (32,800 ft). Modifications such as reduction of fuel and ordnance were attempted to raise performance, to little avail, and in the end aircraft were used effectively in aerial ramming attacks. They were also used in kamikaze attacks, such as the attack on on 2 April 1945 off Okinawa. The commanding officer and 54 crew were killed when a Toryu clipped the stacks from astern, and rammed the bridge. A second Toryu hit the foredeck, opening a 7 m (23 ft) hole in the deck. The ensuing fires demolished the ship, and after the surviving crew was rescued by fellow fast transports, destroyer escort and destroyer-transport , the ship was towed out to sea and scuttled. In 1945, the forward and upward-firing guns showed some results with the commencement of night time bombing raids, but the lack of radar was a considerable handicap. By the spring of 1945, the advent of American carrier-based fighters