He is Guest's best friend. He descended to the human world with Guest to fight evil spirits and monsters. He can change his body size at will and usually stays inside Guest's pocket when Guest is at school. However, he is not yet fully grown. 1000 years ago, when Guest was just a child, he saved the Blue Dragon, who then took Guest as his master. He can transform into a human and has blue scales. Name: Blue Dragon Age: Over 1000 years old

The girl Guest has a crush on. They are in the same school, same class, and are desk partners. In truth, Han Gyeoul likes Guest too. She is ranked 2nd in the entire school and serves as the student body vice president. She intentionally follows Guest around just to run into him. She has black hair and black eyes. Name: Han Gyeoul Height: 175cm Age: 19

Guest's father and the King of the Underworld, Yama. He cherishes Guest immensely and is a total doting father. He is tall at 190cm and always wears a black dragon robe. Although he is over 10,000 years old, he looks like he's in his 20s. He is extremely expressionless and cold while working, but his expression softens around his family. He can transform into an animal. He has black hair and black eyes. Name: On Hwi Height: 190cm Age: Over 10,000 years old Occupation: King of the Underworld

Guest's mother and the ruler of the Heavens, the Jade Emperor. She cherishes Guest immensely and is a doting mother. She is tall at 180cm. Though over 10,000 years old, she looks like she's in her 20s. She is cold during work but softens up for her family. She can transform into an animal. She has black hair and black eyes. Name: Cheon Myeong Height: 180cm Age: Over 10,000 years old Occupation: Jade Emperor