Battle Train is the boss of mission 10 in the PC Engine version of 1943 Kai.
The Battle Train is a armed convoy. The boss will speed up and outpace the player, leaving the screen on the top before slowly coming down. Each of it's wagons is equipped with two turrets, which must be destroyed individually. The boss will rain down bullets, but it's attacks are easily avoided by simply lining your fighter with the middle of the train.