Seisui Kakumei: Omorashi Seijo wa Sono Seisui de Musou suru

"The holy water is basically pee, right...?!" Suzuna stopped going to school because she hated having to pee there, and with the help of her sister, a manga artist, she has been working as her assistant instead. One day, after one too many all-nighters, she misstepped on the stairs and fell… She thought she was dead, but she was instead reincarnated as the saintess in her sister's serialized manga Seijo no Oseisui ga Banouyaku de Isekai Musou (The Saint's Holy Water Is the Source of Isekai Power)! The story of unrivaled peeing in another world begins! (Source: Comic Gamma Plus, translated)