Meruru

Debuted on episode 228. Meruru is a member of Keron's official postal service, who comes to Earth to deliver a message for Keroro, which he tries to avoid receiving, thinking that it is a message from head quarters (but turns out to be a letter from Shipepe, Keroro, Giroro and Dororo's long time friend). Meruru is dedicated to her job to the point that she maneuvers her way around all of the platoon's attempts to detain her, including cloaking devices, guns loaded with capsules of sticky gunk, evasive driving and Tamama's farting (which Meruru isn't slightly bothered by and possibly likes). Meruru's symbol is an envelope.

(Source: Wikipedia)