Fluidrat

Sainen is a writer who works on urban legends. One day, he comes across Mizuki, a sloppy-looking woman who is being chased. Intrigued, he flies to her rescue and decides to take her out to dinner to find out what she is hiding, when men in uniform show up to capture her. The improbable happens when Mizuki, in contact with blood, turns into a rat to escape. Fascinated, Sainen sets out to find the beautiful woman in distress.

(Source: Mangas.io, translated)