the world is inhabited by both humans and monsters. The human population constitutes 65% of the total population, while monsters make up 45%. Monsters are humans who have committed the original sin and can become titans by killing or having killing intent ¹.

Humans possess a power called energy, which comes in three different types: red, blue, and yellow. Humans who use this power are called pags. However, only 14% of humans can have two of these colors than one, while 2% can use a special energy outside of the color triangle called legend the most powerful energy in the world. Note is a legend how's weaker than other legends and the common ones ¹.

Leon, a monster, offers his help to train Note to become a paladin.