When a Plague Doctor Walks the Apocalypse, But He Has White Hair

It all started with a small-scale outbreak of a variant of rabies in Southeast Asia. As soon as the virus was added to the government's monitoring list, it seemed like a premeditated attack. Hospitals all over the world received at least hundreds of patients with the variant of rabies. Unsurprisingly, the apocalypse broke out, and it was unstoppable.

Mu Bai, a college freshman reporting for duty, wakes up after being bitten by an infected person, only to find herself inexplicably transformed into... a white-haired anime girl? Beside her lies something resembling a bird-beak mask...

After the decades-long crisis was brought under control, a survivor of the apocalypse told a story in a restaurant... There was a strange doctor who wore a bird-beak mask, was highly skilled in medicine, and no one had ever seen his true face.

She wandered the wasteland, helping survivors. According to some survivors who died or went missing before the crisis was brought under control, she was a strange person. No one knew how to get this doctor to help them, but she was indeed highly skilled in medicine and even invented various miraculous drugs such as antidotes and inhibitors. The strange person experimented on zombies, and some zombies or infected animals did not attack her. Even more audacious claims were that she could control zombie rat hordes and several special mutants, the survivor said in the restaurant.

This story is interesting, isn't it? Even though the survivor kept repeating it, he wasn't actually telling a story...

(No superpowers + white hair + apocalypse + plague doctor + firearms + single female lead)