Niwa ni wa Niwa Niwatori ga Itaにわ に はにわ にわとり が いた; 院子里曾有两只鸡

A strange world where aliens have taken over the human world, and only two humans are left which are apparently disguising themselves as mere chickens. Fujimoto Tatsuki's first one-shot when he was only 17, and it also contains a special interview section!