If you're looking for manga similar to Mentori, you might like these titles.
One day something emerges from high school girl Kaho’s refrigerator—an emperor penguin, the largest of all penguins! When this emperor joins the household, fun and wacky antics with family and friends ensue!
Pen-Pen, the hat-and-tie-wearing prince of Penguin Land, turns up unexpectedly on little Mika's doorstep. and invites himself and his zany friends to stay.