The pre-dawn mountain chill was biting, but not as sharp as the crushing weight of regret Issei felt throughout his entire body.
"Gah!" Issei fell to his knees, his hands sinking into the cold earth. "Ddraig... this is... too much! It feels like there's a truck sitting on each of my shoulders."
"Don't complain, partner," Ddraig's voice resonated in his mind with a barely concealed tone of satisfaction. "I've just activated the first gravity seal. Your body weight has now tripled. If you want to regain your future strength, your current body must learn to endure the pressure from scratch."
Issei gritted his teeth. His muscles, which had yet to undergo devil training, trembled violently. He tried to stand, but every inch he rose felt like pure torture.
"Remember why we are here, Issei," Ddraig continued, her tone turning serious. "Trihexa will show no mercy. Rias and the others won't remember what you sacrificed, so you must be strong enough so they never have to face that pain again."
The image of Rias crying in the middle of the battlefield flashed through Issei's mind. That memory was like a shot of adrenaline. With a shout of determination, he managed to stand up, though his legs felt like jelly.
"You're right..." Issei gasped, wiping away sweat. "I won't let that future repeat itself. Let's go, Ddraig! Tell me what's next!"
"I like that attitude. Now, climb to the top of that ridge. And remember: no using the Boosted Gear to help you. If you do, I'll double the gravity."
Issei took his first step, feeling his lungs burn.
"Hey, Ddraig..." Issei muttered through clenched teeth as he began to scale the rocks. "This wouldn't happen to have anything to do with what I said about the 'Oppai Dragon' earlier, would it?"
There was a brief silence before the dragon responded with a low internal chuckle.
"Me? A Heavenly Dragon holding a grudge over such a ridiculous nickname? Let's just say... the path to greatness is a heavy one, partner. Now move! You still have five kilometers of climbing to go!"
Issei let out a bitter laugh. He knew Ddraig was punishing him a little, but deep down, he was grateful to have his friend pushing him to the limit. The training to change destiny had just begun.
Sweat soaked Issei's clothes, but he didn't have time to even blink.
"Partner, strength without speed just makes you a sturdier punching bag!" Ddraig's voice bellowed inside his mind. "And speed without power is like chipping stone with a toothpick! Move!"
Ddraig activated a secondary function of the seals. Not only did Issei's body feel heavy as lead, but now small bursts of crimson energy began to erupt from the ground, firing at him like projectiles.
"Dammit!" Issei lunged to the side. His feet sank several inches into the dirt due to the increased gravity, but he managed to dodge the first impact. "My legs weigh a ton, Ddraig!"
"Brute force, Issei!" the dragon shouted. "Don't try to move like a human. Drive into the ground with the intent to shatter it. Use your muscles to explode into every step. If you want to defeat the Fallen and protect Rias, you need every one of your blows to carry the weight of a mountain and the speed of lightning."
Issei closed his eyes for a split second, concentrating. He recalled the sensation of his devil body from the future. He flexed his knees, ignoring the stinging pain in his thighs, and instead of a normal step, he performed a burst of force. The ground beneath his feet cracked, and he shot forward, leaving a trail of dust in his wake.
"That's it!" Ddraig exclaimed. "Now, while maintaining that speed, destroy that rock up ahead!"
In front of him was a boulder the size of a small car. Issei didn't slow down; on the contrary, he accelerated. He focused all his will into his right fist. Although he couldn't summon the full gauntlet yet, a faint reddish aura coated his knuckles.
"HAAAAA!" Issei's scream tore through the mountain silence.
His fist slammed into the stone. The shock vibrated through his entire arm, threatening to dislocate his shoulder, but the boulder shattered into a thousand pieces under the combined pressure of his speed and newfound brute force.
Issei landed heavily, panting, his knuckles bloodied but with a fierce smile on his face.
"Not bad..." Ddraig commented, though she immediately increased the gravity pressure. "But that was just one stone. Now, try dodging ten projectiles while running uphill. If they hit you, we start from zero!"
"You're a sadist, Ddraig..." Issei muttered, but his eyes shone with determination. "Again!"
The first week was, quite literally, hell. Issei could barely stay upright under the weight of Ddraig's gravity seals. Every step toward the mountain peak felt as if he were carrying a building. His muscles burned and his lungs screamed for air, but every time his knees hit the ground, the image of Rias and Akeno in the future forced him back up.
"It's not enough, partner!" Ddraig roared in his mind. "If a Fallen Angel finds you now, you'll be nothing but a grease stain on the floor! Strength! Speed! Stop moving like a human and start hitting like a dragon!"
Issei gritted his teeth, his face caked in sweat and dirt.
"Shut up... and increase... the gravity!" Issei managed to say between gasps.
Ddraig let out a fierce laugh and, suddenly, the pressure doubled. Issei's bones creaked. The young man didn't stop; instead of walking, he began to sprint uphill. Each stride cracked the stone beneath his feet. He was using pure brute force to overcome the gravity.
Upon reaching a small clearing, Ddraig changed tactics.
"Now, dodge this."
Small spheres of crimson energy began to rain from the trees, fired by the dragon's will. Issei, his body heavy from the seals, had to react in milliseconds. At first, the spheres hit him constantly, throwing him against the trees, but by the third week, something changed.
issei stopped "thinking" about the movement. His body, adapted to the constant pressure, began to move by pure instinct. In a burst of speed, he vanished from his position just before five spheres struck where he had been standing. He reappeared in front of a giant rock and, without hesitation, threw a punch charged with all the inertia of his sprint.
BOOM!
The rock didn't just break; it exploded into tiny fragments. Issei looked at his fist; he hadn't used the Boosted Gear—it was just his physical strength enhanced by extreme training.
"Not bad, Issei," Ddraig commented, this time with respect. "Your body is finally ceasing to be that of an ordinary teenager. Your reaction speed has surpassed that of a low-class devil, and your brute force is starting to get scary."
Issei took a fighting stance, feeling energy flow through his veins with a stability he never had in his previous life.
"This is only the beginning, Ddraig," Issei said with a sharp gaze. "I still have five weeks before Raynare appears. By the time that happens, I want to be ready for whatever comes."
Only three days remained until the time he first met the Fallen who murdered him. The mountain peak was shrouded in a storm that Issei's own power seemed to have summoned.
"Gravity seal at 100%!" Ddraig roared. "If you survive this, partner, your human body will be capable of containing the Boosted Gear without exploding!"
Issei felt as if the world were collapsing on him. The ground sank nearly ten centimeters beneath his feet. The pressure was so brutal that any normal human would have been crushed instantly, but Issei only smirked, baring his fangs.
"Bring it on, Ddraig!" Issei challenged.
Suddenly, hundreds of crimson energy projectiles erupted from all directions, moving at sonic speeds. Issei closed his eyes. He no longer needed to see them; he could feel the vibrations in the air.
In a burst of pure speed, Issei became a brown-haired blur. He was moving so fast that it looked as if there were multiple "Isseis" in the clearing at once. He dodged the attacks by mere millimeters, using the gravitational force to propel himself with even more power.
"Now, demonstrate your brute force!" the dragon roared.
Issei leaped toward a massive rock wall, twenty meters high. In mid-air, he concentrated all his energy into his right fist. He didn't summon the gauntlet, but a crimson-red pressure surrounded his arm, making the air itself vibrate.
"DRAGON SMASH!" Issei bellowed.
The impact didn't just break the rock; it pulverized it. A shockwave swept across the mountain peak, dissipating the storm clouds and leaving a massive crater where the stone wall once stood.
Issei landed gracefully, without panting, in a state of absolute calm. The gravity seal deactivated, and suddenly, Issei felt so light it seemed as if he could fly.
"Incredible..." Ddraig admitted, awestruck. "You've managed to fuse your speed and strength into a single flow. Your current body is more resilient than many Ultimate-class devils, and you haven't even used a Chess Piece yet."
Issei looked at his hands. They were scarred from the training, but they felt more powerful than ever.
"Two months..." Issei whispered, looking toward Kuoh Town in the distance. "I'm ready. This time, Rias, there won't be a Pawn in need of saving. This time, I will be your shield and your sword from day one."
Ddraig let out a proud laugh.
"Then let's head down, partner. It's time for Kuoh Academy to meet the new Issei Hyoudou."