"Dad? What's happening?" the young prince of the Kaibutsu or Monster Kingdom asks his father. But before he knows it, the king has thrust him into the human world. Prince Taro (Satoshi Ohno), also known as Kaibutsu-kun must live among people for a while as part of a grooming process before taking over the kingdom. So begins the sometimes scary, sometimes touching and often very funny adventures of Kaibutsu-kun and his three affable attendants Dracula (Norito Yashima), Wolfman (Ryuhei Ueshima) and Franken (Choi Hong-Man).

The monsters meet humans Hiroshi (Tatsuomi Hamada) and his older sister Utako (Umika Kawashima), and through them, they learn about friendship, love, family, and ultimately, the purpose of their mission: what it takes to be a leader.

Kaibutsu-kun is the dramatization of a classic and beloved Japanese manga from the 1960s. In this adaptation, the prince will be played by Satoshi Ohno, leader of the pop idol group ARASHI.