TV-Series
Description
Sadami Natsuiri is a scientist affiliated with the IX corporation in the anime M3 the dark metal. He is the creator of the MA-Vess mecha and the LIM system, technologies central to the story's conflict against the Necrometal and the Lightless Realm. His background reveals that he once collaborated with Mimei Suzaki, the older sister of the character Minashi, on research aimed at enabling people to understand one another without spoken language. This partnership ended when Natsuiri's growing obsession with his experiments led him to secretly use Mimei as the first test subject for the LIM project, betraying her trust.

Personalitywise, Natsuiri is highly eccentric and driven by an intense curiosity about the Lightless Realm. He displays little regard for ethical boundaries, viewing the pilots and even his former colleague as means to further his research. His motivation is rooted in a desire to uncover the truth behind the Lightless Realm and to perfect his methods of linking human thoughts, a pursuit that overrides any personal connections or moral considerations.

In the story, Natsuiri serves as a supporting character who provides technological support to Team Gargouille while simultaneously advancing his own secret agenda. His role becomes increasingly antagonistic as his past actions on Yomijima are revealed. He had previously visited the island to find more candidates for his experiments, using the inhabitants as test subjects and driving many to suicide. Mimei discovered the truth and attempted to flee, but Natsuiri captured her and turned her into the first LIM. This history forms a key relationship: his former partnership with Mimei, which ended in her transformation and eventual fate.

Natsuiri's development sees him become a victim of his own obsession. When he returns to Yomijima to confront the members of Team Gargouille, who have gone there to uncover the secrets of the Lightless Realm, he succumbs to the Necrometal and is transformed into a Necrometal entity himself. This outcome reflects the consequences of his relentless pursuit of knowledge without regard for humanity.

His notable abilities lie in his scientific expertise. He is responsible for developing the MA-Vess units, which are the primary weapons used against the Corpses, and the LIM system, which allows a pilot to merge with their mecha and access greater power by sacrificing their human form. He also displays a manipulative intelligence, using the pilots' circumstances to further his experiments.