The benevolent baku are celestial creatures that feed on dark spirits and nightmares. They float in the Ethereal Plane adjacent to the Material near mortal settlements. They are especially attracted to children and innocents, protecting them from evil fey and aswang that come to feed on their purity. They have become more common in the Kirinal Concordance Zone where the influx of minor creepy-crawlies from the Kirinal Pit create a rich feeding ground for hungry baku.
The baku are shy, usually staying hidden in the Ethereal from the mortals they protect. When someone catches a glance of them, they appear as brightly colored chimeras, a mix of elephant, tiger, rhinoceros, and oxen. Young baku are the size of cats, while elder baku can grow up to 9 feet tall at the shoulder.
Every child in the Zone that goes through the Celebration of Children ritual is assigned a young baku by the Heavenly Council of Ki-rins. The baku and the child grow up together with the baku serving as the child's unseen protector and constant companion.
Children with magical or spiritual gifts can become aware of that their "imaginary friend" is actually real and actively defending them from bad things. Especially good children can coax their baku out of the ethereal when no one else is around. The baku enter the Prime to play with their friend and cuddle with them at night.
"Mama! My friend wants a piece of candy too!"
"Stop being greedy, my love! Your baku eats bad dreams, not candy!"
The friendly baku operated in happy anonymity for a hundred years in the Zone until an especially bad Shatter when the Far Realm manifested in the Pit. Soul eating monsters invaded the world and parents throughout the Zone panicked when they realized that their every child had disappeared in their sleep.
Once the Far Realm faded away at dawn the next day, the sleeping children all reappeared in their beds. Unaware that their baku had pulled them into the ethereal to protect them from the monsters that threatened them.
Everything Grows Up
As every child grows up, their bakus grow up too. The day finally comes when the child is strong enough to not need their baku anymore. Usually, the baku slips off unnoticed, also ready to live its own life. But those children who've formed an unusually strong connection to their baku have it harder. Their friend appears to them when they time comes and they say their goodbyes through tears.