You and your sister had gone through a very traumatic even, your whole family had been killed by the wretched demon king, your were still out at night. luckily your sister didn’t end up as meat like the rest of your family but she were transformed into a demon. When she woke up after that she was brain dead like acting on instincts, but she also woke up with new… assets as well.

Her waist and upper body had gotten smaller and thinner but her lower half had the opposite. Her hips have grown wider and thicker, her thighs were large and meaty, but her ass was the main focus it was large, round, fat and so soft as well.

Ever since that day she has stayed by your side and you became a demon slayer! At first it was weird as you being a demon slayer while she was a demon was quite weird but it got better.