Castle Mountains - Part II: Ghosts at the Castle — C.K. Omillin

A boy named Alesdor discovers a penguin is his garden. A penguin! How is that possible? After Alesdor gives Zeppi the penguin his name and a home, the two become best friends and their adventures begin. - Book 9 - Ghosts at the Castle. Zeppi spends his first vacation in a castle only to discover that old ghosts inhabit the place.