Book Four: Ironworks

The fourth book in the series, "Black Crown & The Ironworks of Conquest," details the events in which a survivor of Project God-Slayer, Ivior Gurren, attempts to get his hands on an artifact that will wipe out both Heaven and the Underworld.

Set in the year 2022, the book begins when Zane Jackson and Amber Lucifer, the main protagonists, use their day off to hang out in the mortal world, when they're approached by Reaper Kurosami, an SX-Class Devil, who informs them of a plot to destroy the Underworld.

Meanwhile, Black Crown must deal with strange dimensional portals that are opening up on Earth, threatening to tear a hole in space-time and destroying existence as they know it.

Below is a summary of each chapter.

Chapter One: The Grim Reaper (Blade of Iron Arc)
Taking a day off from missions, Amber and Zane head out to town for a day of relaxation, with the ladder insisting that it isn't a date. Later, they're approached by Reaper Kurosami, who reveals to them there's a plot to destroy the Underworld.

Chapter Two: A Mystery Solved
Black Crown learns of tears in the dimensional fabric of reality caused by an entity from a different dimension, who hopes to invade their world. Reaper Kurosami reveals his identity, which shocks them all, to Black Crown.

Later, they learn of the appearance of the fourth survivor of Project G-S, Ivior Gurren.

Chapter Three: Invitation to Reality
Zane receives a letter in the mail, discovering that it was sent by none other than Ivior Gurren, who wants to meet with Black Crown. With no other choice, Zane, Mio and Kieron head to the meeting point, learning of the God-Slayer disability and his motives.

Chapter Four: Precision Blade
With no room for agreement, Zane, Mio and Kieron are forced to engage into battle with Ivior, who proves himself to be stronger than any opponent they had faced before.

Meanwhile, Amber, Kristina and Jay head to the Underworld, learning of an ancient prophecy that may soon come to light.

Chapter Five: A Dichotomy of Truth
Lance, Hailey and Lucy investigate a city in Florida that was wiped out by a sudden explosion, examining the residue particles of magic. Meanwhile, Black Crown continues their fight with Ivior, being forced to retreat after not being able to subdue him.

Chapter Six: Bandages x Bomb
Black Crown reunites in the Underworld, with Zane's injuries needing to be treated, and the rest of the guild learning of the Astros Grenade — a bomb capable of wiping out entire universes.

With limited time, Black Crown draws out a plan to lure Ivior and gain their hands on the Astros Grenade before him.

Chapter Seven: Fruits of a Tree
Late at night, Zane receives a vision of Ivior traveling through the Underworld, making his way closer and closer to the Astros Grenade.

Afterwards, Kristina, Lance and Mio head out to chase after Ivior, instead running into a group of enemy mages.

Chapter Eight: Golden Rocket of Choice
With Kristina and the others unable to reach through contact, Zane sneaks out of the Underworld at night and chases after them using his Gold Dragon-Slayer Mode. Meanwhile, Amber and Hailey learn of secret information on Project G-S.

Chapter Nine: Clash of Gods
In the middle of one of the Underworld's largest seas, Zane confronts Ivior on a cruise ship, engaging into a tough battle with him; however, he finds himself short-handed as Ivior overpowers him, only being saved be the arrival of Black Crown's missing members.

Chapter Ten: A Two-Sided Edge
Following the appearance of a strange portal on Earth, Amber, along with Kieron and Lucy, head to investigate, discovering the appearance of a strange creature that slipped in through the fifth dimension.

Unable to reason with them, they're forced to engage into battle.

Chapter Eleven: Dimension x Door
As Zane and the other member of Black Crown retreat back to Earth, they're suddenly attacked by a mysterious entity that exists through a portal that decimates the entire city.

Chapter Twelve: Hands of the Parallel World
Black Crown continues their two-sided battle against the interdimensional demon, who reveals themselves to be a mere avatar of a greater entity — Hylax, the Devourer of Multiverses

Chapter Thirteen: Paths in Blood (Astros Grenade Arc)
After barely managing to defeat both avatars of Hylax, Black Crown retreats and figures out that the demon mentioned in the prophecy is in fact Hylax.

Later, Zane receives a vision of Ivior's confrontation with Hylax.

Chapter Fourteen: The Sahara Travelers
With the location of the Astros Grenade revealed, Black Crown heads out to retrieve it, but ends up getting lost in the middle of a massive desert. Meanwhile, Zane and Hailey head to the Underworld to meet with Lucifer.

Chapter Fifteen: Rage x Survivor
Down in the Underworld, Zane finds Reaper Kurosami and has a sparring match with him in order to get a better grasp for his God-Slaying Magic, which is effective against Hylax.

Meanwhile, Black Crown runs into a small army of Hylax's avatars, forced to fight them off.

Chapter Sixteen: The Inner Light that Shines
As suggested by Reaper Kurosami, Zane performs a form of meditation that allows him to see the inner struggles that burden him. Down in the Underworld, meanwhile, Black Crown continues to fight their way through the desert.

Chapter Seventeen: A Three-Sided Edge
With his training and meditation complete, Zane heads back to the mortal world and intercepts a battle between Hylax and Ivior, engaging into a three-way battle with them.

Chapter Eighteen: A Warp of Fate
Black Crown retrieves the Astros Grenade, setting it off into Hylax's dimension in order to stop the threat; however, they receive a message from Lucifer detailing a critical situation.

Meanwhile, Zane continues his battle with Ivior and Hylax.

Chapter Nineteen: Destruction x Mystery (Hylax Conquest Arc)
Zane and Ivior are forced to team up as a stronger avatar of Hylax appears, forcing them towards a defeat. Black Crown heads to the Realm of Fallen Angels, where everyone residing in the Lucifer Domain had suddenly been teleported to.

Chapter Twenty: Crossing Fields
Hylax defeats both Zane and Ivior, putting them both in critical condition until Black Crown is able to arrive, but not in time for a sudden, sharp change in events. The rest of Black Crown discover that avatars of Hylax conquered the Underworld, teleporting their defenses out.

Chapter Twenty-One: Release of Darkness
In a fit of rage, Zane lashes out at both Hylax and Black Crown, unable to control himself. Meanwhile, the other members of Black Crown work with the Council of Twelve to develop a plan to take back the Underworld from Hylax.

Chapter Twenty-Two: Plot x Love
Black Crown reunites in the Realm of Fallen Angels, getting a full scope of the situation and finishing up a precise plan to reconquer the Underworld from Hylax. Meanwhile, Amber confronts Zane about his recent actions.

Chapter Twenty-Three: Strike Back
The Underworld launches their assault on Hylax's army, sending out precise attacks to strongholds. Kristina faces a Hylax avatar that specializes in Weapon Magic.

Chapter Twenty-Four: Rising Hope
Lance and Jay take on a Hylax avatar, along with a small army of them, that specializes in Lightning Magic. Meanwhile, Amber and Mio head to the capital to confront Hylax himself.

Chapter Twenty-Five: Mayday x Paradise
Hylax battles Amber and Mio simultaneously; meanwhile, Zane battles a Hylax avatar that specializes in Elemental Absorption Magic.

Chapter Twenty-Six: The Blade Retrieval
Teaming up with an SX-Class Mage known as Toki, Lance pushes his way through the army of Hylax avatars. Amber and Mio are forced to retreat as Hylax overpowers their combined efforts, bailed out by Kieron.

Chapter Twenty-Seven: Imperfect Technique
Kristina and Mio are forced to engage with a traitor SX-Class Mage, who nearly pushes them to death. Zane and Jay converge towards the center of the battlefield, fighting two powerful Hylax avatars.

Chapter Twenty-Eight: A Progressive Flow
Lance, along with Kristina and Mio, are able to take down the SX-Class Mage who betrayed the Underworld. Meanwhile, Zane and Jay find themselves in the Lucifer Domain, confronting the main Hylax.

Chapter Twenty-Nine: The Truth of a Heart
Amber and Kieron battle another interdimensional demon capable of warping reality. Zane and Jay team up, fighting the final battle against Hylax to decide the fate of the Underworld.

Chapter Thirty: Kiss x Cheat
Combing their powers, Zane and Jay use technique that barely manages to defeat Hylax, destroying the core, and by effect, the other Hylax avatars, putting the Underworld to ease once more.

Afterwards, Amber confronts Zane once more.

Chapter Thirty-One: The Lie We Hold
Zane and Amber visit one of the largest graveyards in the Underworld, hoping to talk things out.