Kobold Ninja is one of the possible evolution for Kobold. First seen Day 76 (day 79 in the manga).
They still have a dog face but a slight intelligence in the eyes. For they have the same body figure close as human. although they look slimmer than ordinary kobolds.
When a Kobold ranks up to Kobold Ninja, they have a different weapon than the Kobold Footman such as Kodachi called "Organic Sword". These are the sword version of organic spear.
As the name suggests, they have a skill specialize in espionage and stealth like they were born to do well in this area.