Gebluga Ai

"Gebluga Ai, the White Whale. A beast of sorrow and despair. A creature of rage and death. A mother's rage, crystallized into a blade, a blade it seeks to forever drive into our hearts." 
-Captain Kalii
Gebluga Ai the Devourer, also known as the White Whale, is the divine beast of cetaceans, and goddess of storms. Gebluga Ai was once a regular whale, but when her pup, the Stillborn Spirit, was speared out of her womb by hunters, such an indescribable rage filled her that she underwent apotheosis as her body was dragged off to port. Her skin turned white with rage, and her heart grew black as she developed a deep anger for everything and anything. 
After ascending, she devoured the ships of her hunters whole, and began terrorizing the Akonic seas. Her rampage was only halted when a fisherman's son learned of Gebluga Ai's story, and begged that the sea goddess Titania to return the spirit of her unborn child. The child's pleas weakened the monster mother's heart, and she acquiesced, though the spirit would only be able to return for a single night a year. Upon the break of dawn, the spirit would return to the afterlife, and her mother -eternally divine- would never be able to follow. 
Gebluga Ai has a notorious reputation for being temperamental. At times she will guide children lost at sea back to dry land, and on others she will indiscriminately hunt ships. The only times when her chaos abates is when an undyne hunter defeats her, and attains the title of Foam Champion. Her spirit will then return to the world a year later, ready to hunt again.