From MangaHelpers:
Rintarou is deeply judgmental of women, and hates that his dad has been cheating on his mom with a female neighbor. He does not want to be like his dad, and his thoughts are full of gendered sexual slurs towards his female classmates. The only exception is the most modest girl in his class, Yatsugi Azusa. A mosquito-borne disease seems to be spreading around among the women in his city, whose symptoms are fever and extreme sexual aggressiveness. Will he and Azusa make it through the epidemic?