"Tankman" is an artifact costume in the StrikeForce Kitty series, based on Mega Man X from the video game series of the same name.
StrikeForce Kitty 2
"Tankman" adds 12 strength, 3 health, and 11 speed to that kitten, for a total of 27 strength, 25 health, and 29 speed, from "Cragman".
StrikeForce Kitty: Last Stand
"Tankman" is a cosplay that can be obtained from defeated raccoons in StrikeForce Kitty: Last Stand, look on pages in the "Ranged" category.