Write a lengthy, interesting chapter with plenty of dialogue and expedition of a fanfic with that crosses over High School DxD, Bakemonogatari and Fate/Prisma Illya, in which Rias, the other members of the ORC, Kuoh's Student Council President Sona Sitri and the other members of the Student Council aka Sona's peerage pay a visit to Issei's house in order to check up on him after a sick break. When they knock on the door they are greeted by a surprised Tsukihi Araragi, who along with her older fraternal twin Karen is one of Issei's younger sisters in this story. Rias and Sona are surprised to see Tsukihi and also at the fact that Issei is not an only child, but Koneko shakes her head as she recalled Issei sneaking out of one of his classes to take a call from Karen. Tsukihi is also shocked to see Rias, Sona and their respective peerages as well, as she was worried that Issei was a loner who had no social life at school. After recovering from the shock of the whole affair, Tsukihi invites the Gremory and Sitri heiresses and their peerages for tea, which Sona and Rias graciously accept. As Rias, Sona and the members of the ORC and Student Council wait in the tearoom of the Hyoudou mansion, Sona's sharp eyes notice a framed picture on top of the entertainment set, which shows Issei's parents Gorou and Miki posing with a mysterious sliver haired girl whom Sona quickly recognizes as Irisivel von Einzbern, the de-facto head of and only known survivor of the once infamous Einzbern clan of magi after the mysterious passing of the entire clan under a series of unknown circumstances. Before Sona can voice her suspicions however, the door opens and Tsukihi returns with her older twin sister Karen, along with two younger twin girls who bear both a great resemblance to Irisivel and Issei's dad Gorou. As the Araragi twins, the two mysterious girls and the Gremory and  Sitri peerages talk over tea and biscuits, Tsukihi and Karen reveal that the two younger girls are their younger twin sisters, the reserved and reclusive Illya, who has her mother's white hair, and the preppy and outgoing Chloe, who has pink hair and her father's extroverted attitude. Rias is able to deduce from this that Illya and Chloe are in fact the daughters of Gorou and Irisivel and that Tsukihi and Karen are the daughters of Miki, making Illya and Chloe the younger half-sisters of Tsukihi, Karen and Issei. Sona's queen Tsubaki Shinra, also becomes suspicious when she learns that Miki's maiden name was Tohsaka, sensing the large amounts of magical energy Tsukihi, Karen, Illya and Chloe have. Suddenly, Illya and Chloe's friend Miyu Edelfelt bursts into the room with Illya and Chloe's older sisters Leysritt and Sella, reporting that Issei's fever has gone down and he should make a good recovery soon. Rias and Sona note the blushes on Tsukihi, Karen, Illya and Karen's face whenever the latter four hear of Issei and reluctantly accept the fact that Issei's harem is going to get larger soon. Meanwhile, Sona's Pawn Genshiro Sajii, secretly glowers with jealousy as he witnesses Issei taking his King Sona and Sona's Queen Shinra away from him, which Miyu and Chloe notice. The chapter ends with Reines El-Melloi Archisorte, the heiress of the Clocktower's House of El-Melloi and one of Karen's rivals in the moonlit world, entering the Hyoudou mansion to check on her beloved Issei only to be surprised to see Karen, Tsukihi, Miyu, Illya and Chloe as well as Rias, Sona, and the respective peerages of both Underworld heiresses in Issei's room, crying tears of joy that he is alive and trying to use their magic to see if he is okay. Reines, sensing that Rias, Sona and their Peerages are devils attempts to leave the room, but is spotted by Chloe who mischeviously decides to make her stay to that Reines can confess her love for Issei and join his harem as well.