Toaru Majutsu no Index: New Testament - Volume 9, Afterword

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

He emerged from Hell Tower, one of Earth's most mysterious four forbidden zones, known as the Infernal Black Emperor who strikes terror into the hearts of his enemies!He is also the master of the Yin Yang Divine Needles, instilling fear into the Western world as the Eastern Divine Physician, with the ability to save lives with his left hand and take them with his right!Upon returning to the city, he marries the beautiful CEO of the Eastern Group, only to face his father-in-law's regret at the doorstep.'I excel at two things, saving lives and taking them; the ones I choose to save, not even the King of Hell dares to claim, and those I choose to kill, not even the Heavens can save!' —— Ye Xuan

NightmaresCreatures that appeared from the unknown a millennium ago continuously threatened humanity, pushing and pressuring people who once inhabited it aside. These Entities brought the world into utter chaos, furthering their influence to what was once a land that belonged to its rightful owner.In the end, humanity was forced to adapt.They kept trying different ways to fend off the Nightmares, and the solution they finally settled on was… why not become one themselves?Cesar Sparrow, an unfortunate fellow born in an era full of corruption, horror, and the unknown, was desperately trying to escape from its clutches… until he found an enigmatic, dying eyeball that latched itself onto him.“Hehehe, what a great fellow you are,”“How are you talking—. Just what are you…?”The dying eye that latched itself to his empty, bleeding eye socket chuckled, its voice groggy as it answered.“What do you think am I? I’m just an old and weak Nightmare, Sparrow. Though, you can call me Eyes of Deceit. And I'll borrow your body for a moment if you won't mind. Hehe,”“No, why would I give you my body?! Get the fuck out!”Entrapping himself in a series of encounters, uncovering secrets that belong to the Nightmares… and the humanity wanted to remain hidden, Cesar Sparrow ventures into the unknown.To keep struggling, to keep resisting, to keep persevering… will all that be enough?Will he be finally the one to break the chains humans had found themselves in, ending a millennium of suffering? Or succumb to the curse of the Nightmares?