A futanari fakes being sick to rape her sister.
The Onechanbara video game futa comic RenZetsu no Shimai 2 / RenZetsu Sisters 2 by ML of the Oneekyou group.
Related posts:
An Evil Organization’s Punishment Time Futa Manga by Seres Ryu 
Futanari Teacher’s Non-Education Guidance Manga by Chimeda 
Bayonetta Bitch Witch One Touch Futa Manga by Minazuki Juuzou 
[Futa on Male] Houkago Mesu Ochi Shidou Manga by Kikuichi Monji 
[Futa on Male][Kantai Collection] Ai ni Somete Takao Atago Hen Futa Manga by Minase 
[Fantastic Four] Faraway Four Futa Comic by Briaeros