Tubal Cain occupies Seat II of the Longinus Dreizehn Orden, serving as a mindless undead puppet controlled by Riza Brenner via her Holy Relic, Pallida Mors. This corpse amalgamates the souls and identities of successive cursed wielders from the Sakurai bloodline. The first wielder, Musashi Sakurai, forged this replica of Reinhard Heydrich's Longinuslanze Testament under Heinrich Himmler's orders, inadvertently cursing his lineage. Musashi transformed into Tubal Cain upon wielding it, followed by his granddaughter Rei Sakurai, and later his grandson Kai Sakurai. Kai inherited the mantle after mutually killing his lover Beatrice Waltrud von Kircheisen, whose soul and abilities were absorbed into the amalgamation. Depending on the timeline, Kai's sister Kei Sakurai may also become a vessel. The curse manifests through Wewelsburg Longinus, a shape-shifting weapon corrupting any Sakurai wielder into a zombified state. It typically appears as a massive sword or cannon and inherits a key trait from the original Longinuslanze: absorbing the powers, weapons, and souls of those it kills. This absorption allowed Tubal Cain to assimilate Beatrice's Relic and Briah after her death. The relic's curse ensures successive inheritors physically degrade, though Pallida Mors slows this decay while reinforcing Riza's control. In combat, Tubal Cain leverages multiple Creation Figments (Briah) from past wielders: Musashi's emits area-wide corrosive poison turning victims into undead; Rei's transforms the relic into a long-range poison cannon; Kai's coats the body in corrosive armor rotting anything on contact; Beatrice's enables lightning-speed movement and intangibility by converting the body into electricity. Only one Briah activates at a time, requiring switching between them. Narratively, Tubal Cain operates as Riza's weapon, slaughtering enemies like hypnotized students or attacking protagonists at locations such as the Bottomless Pit. It displays limited autonomy upon hearing Reinhard's name, triggering berserk violence against perceived threats. During the Valhalla incursion in Rea's route, Riza deploys it against Eleonore von Wittenburg, but Samiel incinerates it with minimal effort. Its final destruction occurs in Marie's route, where Samiel obliterates it outright. As an Einherjar of Reinhard's Legion, Tubal Cain transcends conventional existence during god-level conflicts, gaining abstract physiology and conceptual manipulation while fighting alongside other deities. This state remains temporary, reverting to its base undead form outside such events.