Here are the key components of our story: two unusually beautiful boys (known only as Big Master and Small Master), an abandoned church, a blood-buying business, and a homeless young girl named Han-Su – who has unwittingly contracted herself to participate in said business. Big Master wants Han-Su out of the church as soon as possible, but it turns out that each of these characters needs something from each other. Big Master needs customers for blood (and Han-Su's blood asap); Small Master needs a link to the human world, and any way to aggravate Big Master (read: Han-Su); and Han-Su needs to keep away from Big Master long enough to stay in the church until she can afford her own place. It seems the boys might have a lot of time on their hands, but how long does Han-Su have to figure out what she’s gotten herself into?

(Source: Lezhin, edited)