The was a series of four battlecruisers planned for the Imperial Japanese Navy as part of the so-called Eight-eight fleet. The ships were to be named Amagi, Akagi, Atago, and Takao (initially named Ashitaka), after the mountains Amagi, Akagi, Atago, and Takao. The Amagi design was essentially a lengthened version of the Tosa-class battleship, but with a thinner armored belt and deck and a modified secondary battery arrangement.