The Shotgun is a weapon from 1943: The Battle of Midway and it's remake, 1943 Kai: Midway Kaisen. On the original game it is symbolized by a five yellow circle icon, while in the remake it is symbolized by a hollow circle icon.
The shotgun creates a five bullet spread which is capable of destroying enemy shots, however the weapon has very short range and low fire rate, limiting it's usefulness. In the remake the Shotgun is severely improved, with a better fire rate and range, as well as having larger bullets and greater firepower.