All six of my sisters are super cool and naturally promiscuous! But I, their brother, am an otaku virgin. I have no immunity to women at all! So, even if they are my sisters, when I see them wandering around the house in revealing, sexy outfits, I can't help but get an erection. Every time I've hidden it, but one day my erection was found out, and I braced myself for being called 'disgusting!' But surprisingly, my sisters' promiscuous hearts were tickled by my erection, and they started competing to go after my virgin dick...
