Suyatta's Combination Fleet series in the sky has aroused great repercussions in the science fiction market after it was launched with its unique original design and story background. However, only Nagato and Mutsu were too lonely. I-400 and I-401 came to support:

In order to make up for the disadvantage of the number of warships, SRK decided to build a batch of special warships with both reconnaissance and assault functions. This type of special warship is equipped with reconnaissance airships and long-range thrusters. In addition, confidential models of torpedoes and mines were also equipped on battleships for combat testing. These torpedoes have the appearance of a meteorite camouflage. These special warships are called "special-type air submarine ships", and the two known as I-400 and I-401 are currently in service.

In order to deal with the enemy's increasingly powerful anti-potential capacity, the I-401 was replaced with a meteorite-shaped camouflage shield.