I was reincarnated as a villain in -High school DxD - DxD

The first sensation that invades Azekiel is a bone-chilling cold, an impossible cold that he doesn't remember ever feeling before. When he opens his eyes, all he can make out is an overwhelming darkness, broken only by a faint red glow emanating from strange symbols etched into the ground beneath him. The place is a vast, silent cavern, with a heavy, magical air.

Confusion and panic flood through him as he realizes that his body isn't responding as it should. His hands are different: they are paler, stronger, and almost sharp, with black nails that look like claws. As he touches his face, he feels a thick scar running across his cheek, something he didn't have before. He looks around, searching for answers, and finds a broken mirror in the corner. As he sees his reflection, the truth hits him: he is not his old self. He has been reborn.

A voice echoes in his mind, harsh and laden with mockery.

—You are finally awake, Azekiel Balthezar. It has been centuries since someone of your lineage walked among the living. I hope you are prepared to claim your place... or be devoured by those who fear your return.

The voice belongs to the spirit of his Sacred Gear, Umbra Tenebris. With each word, the power contained within it seems to move, like a living shadow within his chest. Azekiel tries to calm himself down and think clearly. He remembers his past life: an average young man, a lover of light novels and anime, obsessed with the High School DxD series. That life was over, but somehow, here he was, in a new body, with a feared name and a destiny he didn't know about.

The first confrontation.

As he tries to adjust to his new reality, a metallic noise interrupts his thoughts. A massive iron door opens at the back of the cavern, and a group of lesser demons enter the place, led by a demonic knight in black armor. Their leader, with bright eyes and an arrogant smile, speaks with contempt:

—So the abomination has finally awakened. I don't know how you came back, Balthezar, but it is our duty to make sure you return to dust.

Azekiel senses something is wrong. He still doesn't fully understand who he is in this world, but his instinct tells him that these demons are not his allies. When they try to attack him, his body reacts on instinct. Shadows begin to emerge from the symbols on the ground, enveloping him like a dark cloak. Umbra Tenebris partially takes control, and his body moves with inhuman speed and strength.

In the chaos of combat, he discovers his ability to manipulate shadows, turning them into blades that disintegrate matter on contact. Despite his lack of experience, the fury of the Sacred Gear and survival instinct lead him to defeat the demons, leaving their leader severely injured. However, Umbra Tenebris' power does not come without a cost: at the end of the fight, he feels a searing pain in his chest, as if something is draining his life energy.

Before the demon leader dies, he stammers a few words that leave Azekiel frozen:

—The underworld will not accept you... and neither will the heroes. You are an anomaly... a mistake that will be corrected.

The Revelation of the Lineage

As the dust of battle settles, Azekiel is faced with the harsh reality: not only is he in the world of High School DxD, but he occupies the place of a doomed character. He searches through the remains of the defeated demons and finds an old book with familiar symbols. Opening it, he begins to understand his identity:

Azekiel Balthezar belonged to one of the most powerful, but also most hated, demonic houses in the underworld. His family was exterminated by betrayal and by his obsession with the dark arts. He is, apparently, the only survivor. This new knowledge fills him with questions and a terrible certainty: if he does not strengthen himself quickly, his life will be in constant danger.