Alien Croco is characterized by four eyes and a large beak. Their society is heavily dependent on mushrooms for both food and fuel, which drives them to constantly seek out and develop new species, collecting various types of mushrooms from different planets. 16 years ago, Alien Croco visited Earth from the Champieme Galaxy and, along with its companions, engaged in mushroom gathering at Mt. Suehiro in Hoshimoto City.

However, during this time, Earth was struck by K-Day, when Monogelos from space came to Hoshimoto City. Although Alien Croco received an urgent message from its companions to evacuate Earth, it got lost and failed to escape in time, leaving it stranded alone on the planet. After wandering through the mountains for several days, it eventually stumbled upon an old, small inn called the Akebono Inn. It transformed into a human and adopted the name Numata, pleading with the inn's owner for a live-in job. Over time, it earned her trust and was eventually entrusted with the role of the inn's clerk.

In a quiet, old shed behind the inn, Alien Croco has been secretly building a small spaceship powered by mushroom spores, using mostly discarded junk as parts. The ship's energy source—a mushroom spore-powered battery—was fully charged with enough energy to return to its home planet. Just as it was about to leave Earth, it was discovered by SKIP members Yuma and Shu, who were investigating mysterious earthquakes and electromagnetic waves.

Interestingly, the hand signs and gestures used by Alien Croco with its hands and fingers carry the meaning of "thank you."