Yu Doha, a veterinarian and trainer at a monster biology facility, becomes an unexpected guardian to a juvenile tentacle monster after a slimy first encounter. Imprinting on Doha as its parental figure, the creature named Octo leaves Doha responsible for its care and training over the next year. However, Octo proves nearly impossible to manage alone due to its unpredictable behavior and insatiable sexual appetite. To ensure Doha's safety, Cha Gyeonghwan, the facility chief’s son, is brought in as his assistant. As they work to tame Octo’s wild tendencies, the two grow unexpectedly close, their connection deepening into something far more personal.