Aren't Guides Allowed to Bite Espers?

Hundreds of years ago, in the heart of the city, a gate appeared. In a world where neither animals nor humans existed, ferocious organic beings called “creatures” emerged. After an accident, S-class guide Sawol, who became a half-creature, half-human ‘creman’, hides this fact and continues to live.

“Sawol, listen to me when I’m speaking nicely. I don’t want to threaten you either.”
“What you’re doing is already a threat.”
“Please, just keep your mouth shut if you find out.”

Instead of protecting her secret, Esper Yugeon, who demands to be paired with her, has a reason for Sawol to avoid him. As a creman, she needs to periodically feed on blood, and Yugeon’s scent is too sweet to resist. Eventually, in order to keep her secret, she decides to be a pair with Yugeon.

“I’ve seen you as a woman for quite some time now.”
“But back then…”
“Back then, I thought I shouldn’t get closer to you.”

Hangyul, Her first love, which she once distanced herself from, begins to approach. He was Yugeon’s older brother. Strangely, as they decide to work together to protect her secret, an incident occurs where only guides are targeted, and strange things start happening around Sawol.

Will Sawol be able to keep her secret until the end?