Ruka

"With this, you won't suffer as you die. Farewell."

A girl whose occupation is unknown. Her name "Ruka" is a nickname and not her real name. She receives dangerous work requests from the group.

Per the group's instruction, she is left to Iwamori's care and starts living in the same apartment as him.

After peeking at Iwamori and Tomoko having sex, Ruka started to have an interest in sex as well.

She then gets addicted to the pleasures she never experienced before, and presses Iwamori for sex often. However, contrary to her appearance, she has great stamina so she requests the protagonist to have sex multiple times in one night, which troubles him.