GOSHIKA Marume

An unidentified flying object suddenly crashes at the United Nations Headquarters in New York. A mysterious being calling himself "Noah" appears. He says he has come to save the Earth, but his purpose is completely unknown. At the same time, a mysterious incident occurs at an elementary school, where 88 people suddenly disappear... In the midst of this unprecedented crisis, the United Nations' supernatural secret analysis department, Black Sheep, is called into action. The key to solving the mystery lies outside of commonsense. (Source: Kodansha, translated)

Warabii Sensei, a quack wallaby from Australia who loves "Bushido". He loves animals! He lives at the home of the principal of the school, who is an animal lover, and leads his students through a mischievous and cute school life! (from mangaupdates)