My Girlfriend is Everyone’s Toilet Bitch

Yuka Ootsuki is my childhood friend who I've been dating since junior high school. She is always cheerful, has a sense of justice, and is popular with both men and women. The couple gets along well and one day they finally spend a night together. Then, a certain test was conducted at the school. It is a test to find out people that have a strong immune system. The result was positive for the girlfriend. The protagonist was gut-punched, but his girlfriend looked somewhat mystified. Sadly, her parents' factory went bankrupt. In other words, her parents' family was heavily in debt and she had to find a job. She ended up accepting a job that would provide immediate income, with the condition of lending her body to others to protect them from the virus. (Spoilers: She turned into a cum dumpster...)