Wow I'm so glad to have another chapter so soon after the last. The art is amazing like always & we sure are in for the ride of our lives. Thanks for the chapter.
In a different manga, we would think that she's inviting him over for a completely innocuous visit, and he's being a pervert for imagining a threesome. In this manga tho...yeah, she's definitely inviting him over for a threesome with her sister.