Detective Hatori on the Case of the Ancient Creature

This is an AU (Alternate Universe) of the Ancient Magus Bride.

Detective Chise Hatori, widely known as one of the most powerful creature catchers in the world, is assigned the case to catch the ancient creature. As a child she was abandoned by her father and her mother passed away, as she grew up alone a man took her in and raised her inside the company. The CCC (Critical Creature Catching) Company raised her and took advantage of the abilities she seemed to posses. Though her abilities are powerful they cause her to grow sick, so scientists developed a medicine to keep her healthy. And in return she uses her abilities to catch these seemingly "Dangerous" creatures. However, once assigned the Ancient Creature, she isn't sure if what she is doing is right. This creature doesn't seem dangerous, nor like a threat, as a matter of fact he doesn't seem like a creature at all. He seems like a living person who doesn't deserve to be executed or locked away... is this right?

(I left the Mature rating off because it shouldn't get to that level. There will be blood and some graphic scenes but that should be all. The romance between the two will be near the end and should be completely appropriate.)