Uhmm, some pages back its explained, but anyway: its more like an Extra Arc or SS composed by 4 releases, each publish on 3 month magazine, its located after Web Arcs on Tats/Miyuki 2nd High School year and so far I know its not related to the main story line, remember the author ready have the web arcs before where hired by Dengeki, after that, Dengeki took the web novel and publish with their style, editing and so far I heard given the chance to the author to enrich the story, so, right now we are on Web Arc 5 = Vol 8 Dengeki, its coming Vamps Arc or Web Arc 6, with the probability of at least 2 more books from Dengeki, until that the main story still freeze their advance, so my POV they did Ninendo or Double 7 with object of given the fans something new (apart from SS) until Dengeki releases get the Web Arc timeline.
Double 7 its focus on new school year and the introduction of Saegusa twins, Mayumi imoutos, among others, the author set the focus on the inside conflict of the 7th Clan, which Saegusa are the Main Branch or Family and Shippou are from side branch upset with the current hierarchy status, his try outs to coup d etat and seems he like to pick a fight with Shiba siblings due their closeness with Mayumi (on their POV specially Tats)
, off course, this guy need a brief from Suzune about Tats, but she on College
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