The cannon system accelerates a shell to hypersonic velocities, allowing it to reach up to 500km in range. The 1200mm shells fired also utilize sequential ignition with inbuilt firing charges, allowing the bullet to gain speed as it travels the length of the cannon's barrel. However, the firing exerts a large amount of stress on the barrel, and three shots are all that it can manage in a short period of time before overheating.
The 1200mm OTH Cannon was used once by Tamase Miki in the events of Muv-Luv Unlimited to shoot down a runaway HSST that was heading for Yokohama Base. It does not appear in Alternative or The Day After.