Yeah, the first episode adapts the first chapter of the Doujin but for some reason they decided to skip the other two chapters with the older sister and jumped straight into chapter four with the younger one. There’s also a third episode coming up adapting the fifth chapter of the doujin. Basically, the first three revolve around the older sister and the next three are about the younger one. It also seems like we’ll get an oyakodon situation here because their mother appeared in the latest chapter but we’ll see. Also, they changed something about the story. The younger sister did not go to the guy’s apartment because she was curious about him based on what her sister told her, it was actually because she wanted to bring her sister back home because she is now staying with him. Dunno why they changed that either.