Investing in My Harem in the Apocalypse Makes Me Stronger

This time, the notification did not belong to Cain alone as every human inside Invasion Corridor 73-A heard it.

At the same time, the same announcement reached humanity throughout the Original World.

[World Announcement]

[The World Gate Core has been destroyed.]

[The permanent dimensional connection established by the Zombie Race has been severed.]

[World-Class Mission: Sever the Zombie Race Invasion has been completed.]

[The Zombie Race invasion through the Invasion Corridor has failed.]

Across Earth, countless humans received the announcement.

Survivors hiding inside ruined cities saw the translucent screen appear before them, while people still fighting against zombies elsewhere finally received notification that the invasion had been stopped.

Inside the underground chamber, another notification appeared before every surviving human who had entered the Invasion Corridor.

[Invasion Corridor 73-A has lost its World Gate Core.]

[Dimensional stability is rapidly decreasing.]

[All surviving human participants will be forcibly transported back to the Original World in 01:00:00.]

[Please complete all remaining activities before the transportation begins.]

Ron stared at the timer.

“An hour.”

Cain glanced at the notification before looking toward the passage they had used to enter.

“That’s enough.”

There was no reason to waste that hour resting while enormous quantities of Cores and Blood Crystals remained scattered throughout the Central Base.

Before Cain could turn away, another notification appeared directly in front of him.

[Ding!]

[Calculating individual contribution to the completed World-Class Mission…]

Cain stopped and looked at the translucent screen as several additional lines appeared.

[Contribution factors include destruction of mission objectives, combat contribution against mission-critical enemies, assistance provided to other participants, and contribution toward destruction of the World Gate Core.]

[Calculation completed.]

[Your individual contribution has been evaluated as the highest among all participants in Invasion Corridor 73-A.]

[World-Class Mission completion reward is being generated according to individual contribution and overall mission difficulty.]

Cain’s eyes lit up.

The original mission description had already stated that the completion reward depended on contribution.

Considering everything he had done inside the Invasion Corridor, Cain had expected something valuable.

The next notification appeared.

[Ding! You have obtained the Divine-rank Talent reward: Dragon Heart.]

Cain raised an eyebrow.

‘Dragon Heart?’

Before Cain could read the description, another notification appeared.

[Ding!]

[Exceptional compatibility detected.]

[Dragon Heart possesses extremely high compatibility with the user’s Primordial Chaos Dragon power.]

[A high-grade reward resource may be consumed to increase the rank of Dragon Heart before acquisition.]

[Eligible resources detected.]

[Red Scroll: 1]

[Red Orb: 1]

[Consume one eligible resource to elevate Dragon Heart from Divine-rank to Origin-rank?]

Cain barely needed to think about it.

The Red Scroll could grant a Talent or Skill compatible with whoever opened it, making it far more flexible and valuable than the Orb.

“Use the Red Orb.”

[Ding! Red Orb selected.]

The crimson sphere disappeared from his Inventory.

Power flowed into the reward before him as the words beside Dragon Heart began changing.

[Ding! Divine-rank Dragon Heart is undergoing evolution.]

The process lasted only a moment.

[Ding! Evolution completed.]

[Dragon Heart has evolved from Divine-rank to Origin-rank.]

[Dragon Heart — Origin-rank Talent]

Cain’s eyes lit up.

Another notification appeared beneath it.

[Origin-rank Dragon Heart is ready to be implemented.]

[Accept reward?]

Cain looked at the notification for several seconds before glancing toward the ruined World Gate Core.

The underground chamber was still unstable as the remaining dimensional energy slowly disappeared.

He also had no idea what kind of change would happen when accepting the Dragon Heart might cause.

Thus, he thought that there was no reason to do it here.

Cain closed the notification without accepting the reward.

“Let’s go back.”

The group turned toward the passage leading to the surface.

Behind them, the final traces of violet energy disappeared from the underground chamber.

The path connecting Earth to the Zombie Race had finally been severed once and for all.

By the time Cain and the others returned to the surface, the Central Base had already become far busier than when they left.

The people who remained behind had spread throughout the ruined fortress and were stripping anything valuable from the battlefield before the System transported them back to the Original World.

Bodies of Zombie Race soldiers were being searched for Cores, Blood Crystals were being removed from storage buildings that had survived the battle, and anything else that looked remotely useful was being gathered near the central avenue.

Cain had barely stepped out of the underground passage when he stopped.

“Keep an eye on the surroundings for a bit.”

Ron glanced toward him.

“What are you doing?”

“I still have something to awaken.”

The others naturally understood what Cain meant and immediately made a distance from him.

Cain chose a relatively intact section of the plaza and sat down cross-legged.

The notification he had deliberately left waiting appeared again the moment he focused on it.

[Origin-rank Dragon Heart is ready to be implemented.]

[Accept reward?]

Cain did not hesitate as he instantly replied.

“Accept.”

[Ding!]

[Origin-rank Dragon Heart integration has begun.]

The first change came from inside his chest.

Cain’s entire body tensed as his heartbeat suddenly became powerful enough that he could hear it clearly without focusing.

Thump!

The sound traveled through his chest with enough force to shake his ribs.

His heart contracted again.

THUMP!

A dense pressure spread outward from the organ and passed through Cain’s body, causing every vessel connected to it to tighten.

The sensation was not exactly painful at first, but the pressure increased with every beat until Cain felt as though something inside his chest was forcing his heart to rebuild itself from the inside.

Cain gritted his teeth.

His Ruin Mana Core reacted next.

True Ruin began circulating on its own, flowing upward from his Core before gathering around his heart.

The dark-gray energy did not attack the organ. Instead, it sank into the flesh and gradually became part of whatever transformation the System had begun.

Another heartbeat followed.

This time, something changed.

The blood leaving Cain’s heart carried a density it had never possessed before.

The difference spread through his arteries with every pulse.

Heat followed soon afterward.

It did not resemble the burning temperature of Purgatory Flame. The sensation came from far deeper, passing through his blood before spreading into his muscles and internal organs.

Cain could feel individual sections of his body reacting as the transformed blood reached them.

His muscles tightened beneath his skin.

The bones throughout his body began producing faint cracking sounds as a powerful pressure reinforced them from within, yet there was no actual damage.

His Mana pathways reacted even more strongly as True Ruin circulated through them with far less resistance than before, and Cain immediately understood that the pathways themselves were being strengthened to endure a much greater amount of energy.

Then the pain finally arrived.

Cain’s fingers dug into his knees.

A portion of the blood flowing through his body was changing.

There was no comfortable sensation accompanying the process. The power contained inside the Dragon Heart invaded the blood directly, transforming part of what had always belonged to a human body into something fundamentally different.

Cain’s breathing became heavier.

Every heartbeat sent more of that transformed blood through his body.

The pressure hidden inside it was enormous.

It carried a quality that reminded Cain of the Primordial Chaos Dragon, although the amount was so insignificant compared to the actual beast that the difference could not even be properly compared.

Still, it was enough to affect Cain.

Dark scales briefly emerged along the back of his hands.

They spread across his wrists before appearing farther up his forearms, darker and denser than the scales he normally produced through Partial Dragon Manifestation.

Cain had not activated the Skill.

The transformation was happening because the blood inside him was responding to the Dragon Heart.

Deep within the Black Menagerie, something stirred.

Cain’s consciousness briefly sensed the familiar presence hidden inside that mysterious inner world.

The Primordial Chaos Dragon did not reveal itself completely.

There was only the faint sensation of something unimaginably ancient becoming aware of what was happening inside Cain’s body.

The Dragon Heart reacted instantly.

THUMP!

A wave of pressure erupted from Cain.

Several people standing farther away turned toward him.

Dust spread outward from the ground surrounding Cain, and cracks appeared beneath where he was sitting.

Ron narrowed his eyes.

“That doesn’t look like some ordinary Talent.”

Elara remained focused on Cain.

“He said he was awakening something. Just let him finish first.”

Another pulse traveled through Cain’s body.

The dark scales covering his arms became clearer before gradually receding beneath his skin.

Cain’s breathing slowly stabilized.

The transformation of his heart had already reached its final stage, yet the Dragon Blood continued circulating through him, forcing the rest of his body to adapt to the new power flowing within it.

His perception became sharper.

Cain could hear people working throughout several nearby streets even though he was not deliberately concentrating on them. He could distinguish the sound of metal striking stone from voices coming from a completely different direction.

Even his awareness of Mana had changed.

The energy moving through the people around him seemed clearer than before.

True Ruin responded with even greater intensity.

Cain experimentally allowed a small amount to circulate through his right arm.

His expression instantly changed.

Previously, sending too much True Ruin through his body eventually placed considerable strain on his muscles and Mana pathways.

The power was inherently destructive, and even his own body could only withstand so much of it at once.

Now the energy flowed through him far more smoothly.

Cain then increased the amount slightly.