MAJOR

Protaganists

Kwon Jooyeon

Debut Appearance: Chapter 01: Pilot
Status: Alive
Skills/Abilities: Fluency in Latin (able to read, understand and speak it) [First appeared: Chapter 01]
Background: She came to Seoul to attend her grandfather's funeral and decided to stay there for the time being. She acquired weird visions after reading a Latin book left for her from her grandfather. She is acquainted with Kim Joonmyun, Byun Baekhyun and Kim Taeyeon(?). 

Kim Taeyeon

Debut Appearance: Chapter 01: Pilot
Status: Alive
Skills/Abilities: N/A
Background: Not much is known of Taeyeon. She appeared to be a close confidant of Grandfather Kwon, and looked after Jooyeon, though the latter was oblivious to that fact. She entrusted Jooyeon the book and insisted that she study that. She showed great hatred towards Yesung.

Kim Joonmyun

Debut Appearance: Chapter 02: Blackout
Status: Alive
Skills/Abilities: N/A
Background: Not much is known of Joonmyun. He is well-acquainted with Jooyeon and Baekhyun. It is mentioned that he is an avid reader and good at making coffee (as stated by Jooyeon that his coffee was 'the best she ever tasted'.)

Byun Baekhyun

Debut Appearance: Chapter 03: Stranger
Status: Alive
Skills/Abilities: N/A
Background: Not much is known of Baekhyun. He is well-acquainted with Joonmyun and later, Jooyeon.

Antagonists

Yesung (Kim Jongwoon)

Debut Appearance: Chapter 03: Stranger
Status: Alive
Skills/Abilities: N/A
Background: Not much is known of Yesung. He appears to be enemies with Taeyeon. He works under the orders of 'Master Park'. He is after Jooyeon and some other people.