Turn into a Girl and Save the World?

(Change+Slight Abuse+Knife+Yandere) Because of an "accidental" accident, Qi Ran's life stopped at the age of 18. But perhaps it was the kindness of "God" that gave her the opportunity and system to be reborn, allowing her to embark on the mission of saving the world. However, this system is always unreliable. Not only does it often give him weird "rewards", it also turns him into a girl! But this is not difficult, as long as you live... Qi Ran, no, Qi Ranran never expected that the novice mission would start in hell! She became the most trusted person of the Demon King but asked her to help the hero save the world? ! And if you fail the mission, you will have to accept very strange punishments...