Mini Octotank No. 8

Mini Octotank No. 8 (ミニタコタンク８号, Minitakotanku 8-gō) is an octopus shaped robot created by Child Emperor that will continue to shoot at any object moving in the alert zone until carbon dioxide emissions is no longer detected.

Monster Association Arc
It kills a monster trying to sneak up on Child Emperor, being destroyed by Phoenix Man.