Haou Airen

One day while walking home from her job, Kurumi Akino finds a wounded young man, and saves his life. He mysteriously disappears after that, and leaves only the name “Hakuron.” Next thing she knows she’s been kidnapped from her school, and is on a private jet with that man, heading to China. It turns out she saved the life of the most infamous mobster in Hong Kong, and he wants her to stay with him.
(Source: Studio MS, translated)
Note: Includes one extra chapter