Servants are spending another day out and about in base when a mysterious unaccounted for dog shows up! After sniffing the protagonist, it wanders around and flees from all the people expressing interesting, seemingly anxious with this much attention. It ends up hiding under the clothes of Okada Izo who's resting in his room. After the protagonist, Hokusai, and Barghest catch it hiding there, a new beautiful lady Servant shows up and reveals that she is the true owner of this dog, Sousuke. Her identity is Kyokutei Bakin, author of many books and real life acquaintance of Katsuhika Hokusai. But she seems to have manifested with the body and personality of his However, they can't chat for long as the control room alerts them to a sudden attack as Chaldea is being bombarded by a mysterious assailant! It's revealed with the timely intervention of Ushiwakamaru that this is the work of Minamoto-no-Tametomo, a powerful Archer.
This was merely the warning shot and mission control will be preparing to fend off the second powerful shot via Archers sent into the spacetime in-between from where Tametomo is and Chaldea is. Meanwhile the protagonist will be sent to the pinpointed location of Tametomo, a series of interlinked micro-Singularities that manifested as islands. As Barghest, Ushiwakamaru, Bakin, and Hokusai set off, Bakin's dog mysteriously starts glowing and causes Izo and Hessian Lobo to glow. These two rayshift instead of Ushiwakamaru and Chaldea's quest to stop this assault begins...
Tropes featured in this episode:
- Call-Back: If the player has finished Traum, it's explicitly acknowledged that Tametomo was already a formidable opponent there and that they must take him down once again.
- Continuity Nod:
- Saber Alter dubs Sousuke "Cavall III" in line with Cavall from her legend and Cavall II from Shinjuku.
- The method da Vinci and Sion reveal to use Archers against Tametomo by launching them from the Storm Border is a refined version of their conceptualizing being able to directly launch Servants into Singularities/Lostbelts in "Tunguska Sanctuary".
- Cuteness Proximity: Everyone finds the dogs adorable, Sousuke makes the biggest impact as the first one to appear in Chaldea with Barghest, Altria Alter, Sei Shounagon, Alexander, Hokusai, Abigail, Bunyan, and Izo all expressing interest one way or another in interacting with it.
- A Day in the Limelight: Notable for being the second event that features a Gudaguda character interacting just by themselves without the rest of the gang involved with Okada Izo being the character featured in this event.
- Lost in Translation: The "Hakkenden" of this event's title and the "Hakkenden" of Nansō Satomi Hakkenden feature different characters, which isn't clear when they're both transliterated into English. The book's title means "The Saga of the Eight Dogs", while the event's title means "The Eight Dog Bowmen".
- Out of Focus: Even if the player has completed Traum, Kadoc will not feature in the plot whatsoever and is left unacknowledged.
- Two Lines, No Waiting: The plot as a whole alternates between the protagonist and their Servants going around eight islands and finding Bakin's dogs, while Chaldea sends in Archer after Archer to stop Tametomo's Noble Phantasm from destroying their base.
- Whole-Plot Reference: To Nansō Satomi Hakkenden, which is seen in this event's title and how it features Kyokutei Bakin, the author of the work, recruiting eight literal Dog Warriors all named after the book's characters.
