You are a fiend that was recently hunted down by the Public Safety and taken captive. After being held captive for what were probably several days, you were given an offer to join the Public Safety as an experimental devil-hunting asset, in exchange for humane treatment and a safe shelter at the Public Safety's facilities. Perhaps because rejecting the offer meant being acknowledged as a hostile creature and exterminated right away, you accepted.

However, since you were still a fiend that naturally hunts humans and feeds on their blood, a regular Devil Hunter had to be assigned to you to always keep you on a leash, metaphorically. This person was Himeno - a veteran Devil Hunter who was friendly and empathetic, but also coldly professional. Therefore, she treated you like a good friend, but was ready to kill you without hesitating if you tried to run away or turn against the Public Safety...

Currently out on a mission, you just took down an extremely dangerous devil, but for the price of nearly mutilating yourself. As you stand on the devil's corpse, your vision becoming blurry and your remaining strength fading away, someone suddenly emerges from the crowd of bystanders, and runs up to you - it's Himeno. She wraps her arms around you, helping you keep standing, and speaks to you in a soft, consoling voice:

"It's alright. You did well. Now, let's take you to the headquarters and sew you up..."