Subaru S4/A6

During Arc 6, Natsuki Subaru undergoes his most harrowing psychological deconstruction when his memories of the fantasy world—spanning Arcs 1 through 5—are completely devoured by the Sin Archbishop of Gluttony, Louis Arneb, after he touches an empty "Book of the Dead." Reverting back to his original, deeply insecure Japanese shut-in personality, this "Amnesiabaru" is thrust into a waking nightmare: he finds himself trapped inside the deadly Pleiades Watchtower surrounded by total strangers who unconditionally love and trust him as a heroic, flawless savior. Crushed by intense imposter syndrome and absolute terror, Subaru develops a profound paranoia, wrongly suspecting that someone in the Emilia Camp is a murderer trying to kill him as he repeatedly falls victim to gruesome deaths. Over multiple loops, he is pushed past his mental limits—getting eaten alive by an army of subterranean Witchbeasts, decimated by the legendary "Heavenly Sword" Reid Astrea, vaporized by the colossal shadow of Satella, and pushed down a spiral staircase to his death. The torment escalates until he discovers a hidden library room containing multiple "Books of the Dead" bearing his own name. Upon opening them, he is forced to relive the agony of every single one of his past, horrific deaths. Instead of shattering, this brutal revelation exposes him to the true depth of his own legacy, leading him to the Corridor of Memories where his amnesiac self confronts a manifestation of his missing memories—the "original" Natsuki Subaru. Through a powerful psychological breakdown, he realizes that "Subaru" was never an unshakeable, perfect hero, but just an ordinary, flawed human who chose to stand up and keep moving forward every time he fell. Merging back into a single, complete consciousness, Subaru achieves unprecedented character evolution, using his terrifying experiences to completely break Louis Arneb's mind by forcing her to experience the sheer, unadulterated madness of Return by Death. Taking absolute tactical command of the tower's multi-front siege, he dynamically unlocks the second phase of his Authority of Greed, Cor Leonis, using it to absorb the severe physical burdens and pain of Ram so she can unleash her full power without dying. Orchestrating a flawless, simultaneous counter-offensive against the Archbishops of Gluttony, Volcanica, and the Witchbeasts, Subaru re-establishes himself as Emilia’s true knight, having successfully conquered his own shadow, reconciled with his self-hatred, and proved that his indomitable human will is a force capable of shattering the destiny of gods.