Shokudô no oneesan: Inran ni jimi-jiru

Original title: 食堂のお姉さん 淫乱にじみ汁

K-ko runs a casual eatery in Tokyo’s old downtown district. She has a spirited, straightforward personality; though she tends to lecture others, she possesses a charm that brings people together. One day, she happens to visit a "happening bar" (an adult-oriented social club) after being taken there by a customer from her shop. There, she spots a senior figure from her hometown—someone she has long admired—playing the piano...