Astral Chain (Nintendo Cinematic Universe)

Astral Chain is a Japanese graphic novel.

Summary
Two twins from the Neuron task force are assigned to protect remnants of humanity from interdimensional creatures and aberrations that invade the planet

Plot Elements

 * Protagonist and Akira are dispatched to respond to an aberration attack, but are quickly outmatched by Chimeras.
 * The twins are saved by Neuron officers Max, Alicia, and Jin, who wield Legions capable of fighting them. Yoseph assigns Legions to Protagonist and Akira, enabling them to repel the Chimeras.
 * Afterwards, the twins are both formally inducted into Neuron. Their first investigation mission goes awry when Protagonist ends up being pulled into the Astral Plane, causing the rest of the squad to pursue them into the Astral Plane to save them. Due to prolonged Astral Plane exposure having the effect of weakening humans, the Neuron officers lose control over their Legions, causing them to break free and go berserk.
 * In the end, only Protagonist is successful in subduing their Legion.
 * Max battles the remaining frenzied Legions and sacrifices himself to allow the rest of the squad to escape.
 * Meanwhile, Neuron's Legion production facility is attacked and put out of commission, leaving Protagonist as the only officer with access to a Legion.
 * Protagonist is sent on further missions to respond to Chimera attacks, eventually recapturing the lost Legions in the process.
 * During this time, the twins come into contact with Dr. Jena Anderson, a former pupil of Yoseph's who is instigating Chimera attacks and bears a grudge against UNION, the Ark's ruling government. She manages to critically wound Akira while evading capture, leaving clues to Protagonist to investigate Zone 09, a quarantined section of the Ark which Neuron officers are forbidden from entering.
 * Protagonist goes undercover and explores Zone 09 with Hal, discovering that UNION developed a drug called Blue Evolve that could allow humans to fight Chimeras, which also carried the side effect of turning the users into Aberrations. After battling one of Jena's chimeric homonculi, they are saved by a recovered Akira, who has obtained a new Legion.
 * As a result of entering Zone 09 without permission, Protagonist is jailed for insubordination, and Hal goes into hiding to avoid arrest.
 * After another wave of Chimera attacks occur, Neuron is forced to provisionally release the Player to combat them.
 * Jena stages a large scale invasion of the Ark, announcing her intention to save humanity by merging Earth with the Astral Plane, which serves as a collective memory bank of humanity.
 * The skirmish leaves Neuron's headquarters defenseless, allowing Jena to infiltrate it and take Yoseph hostage.
 * The twins arrive to rescue Yoseph, causing Jena to power herself up with Blue Evolve before battling Protagonist.
 * During the battle, Protagonist unwittingly ends up fully merging with their Legion and goes berserk, attacking Akira.
 * Jena sacrifices herself by distracting the transformed Protagonist, telling them that this is the true form of their power.
 * Yoseph then calls in the Ravens—a newly created task force of Legion users—and orders them to kill Protagonist, causing them to fall off an overpass.
 * Protagonist wakes up back in their human form, having been rescued by Hal and Olive, and brought into a hiding place in Zone 09.
 * Hal explains that Yoseph has largely replaced Neuron with the Ravens and is actively hunting Protagonist, accusing them of treason.
 * While carrying out a covert rescue operation to retrieve Brenda from Neuron, the crew are confronted by Akira, who tries to convince Protagonist to return to Neuron, but they are ambushed by the Raven unit, revealing themselves to be clones of Akira.
 * The Ravens attack Akira, causing Akira to inadvertently merge with their Legion and go on a rampage.
 * To stop Akira, Protagonist willingly merges with their own Legion and manages to knock Akira back into their human form.
 * Wanting to find out and stop Yoseph's plans, the twins stage an assault on his lab.
 * After being confronted, Yoseph uses the Ravens as a catalyst to create the ultimate Legion, Noah, and merges himself with it, intending to absorb all life on Earth in order to become a god.
 * Akira ends up being absorbed into Noah while trying to protect Protaonist.
 * Protagonist battles Noah and weakens him enough to allow Akira to temporarily seize control of Noah's body, allowing the Player to destroy Noah, but killing Akira in the process.
 * Following Noah's destruction, Chimera attacks begin to decrease drastically, allowing humans to consider leaving the Ark and repopulating the Earth.
 * Alicia and Jin put Neuron back together, with Olive as interim commander, and the task force continues to handle the few Chimera attacks that still occur on the Ark.
 * Akira is revealed to have survived through one of their remaining clones, having been transplanted memories by Brenda using traces found in the original's Legion.