During the Events of Starfy 4, Dejiru, along with King Owlrune, took control of the Amiy Island.
Mattel, a maiden of the castle and the love interest of Prince Coral, barely escaped with her life to Pufftop, where she sought the help of Starfy.
Meanwhile, Dejiru cast vile magic and took control of 8 enemies, to exude her power, via manipulation of the Peace Heart.
Starfy and Co. Battled their way through scores of monsters, and reached Amiy Castle!
After fighting their way to the top floor, Starfy confronted the mad Serpian.
After a long and grueling fight, Dejiru was defeated, and the magic of the Peace Heart disarmed her by turning her into a harmless Sea Krait.
The Kingdom returned to normal, and within a month, Mattel and Coral were wed, much to the dismay of Starfy and Starly.