In DxD Starting with Sign-Ing in as the Red Dragon

The contract has been established.

Rias paid the price to ask Chiba Akira to act as a shield.

And Akira willingly became a mercenary.

After all, he was very poor.

Moreover, the identity of being the heir of the Leviathan bloodline would soon lose its benefits.

He needed to cash in quickly before it was completely gone, squeezing out the last bit of value.

...

Thus,

When leaving the old school building, Akira had several small boxes added to his pocket.

These were the deposits Rias had given him.

The remaining monster corpses would be gathered by Rias as soon as possible.

....

"A year's worth is definitely enough for Agumon to evolve."

"This is also thanks to Rias."

"Although she also has her own motives for using me, this is just how the world operates."

"Using me and mutually benefiting each other reflects my value."

"If no one wants to use you, it only shows your incompetence."

After silently thanking Rias, Akira took one last glance at the old school building.

Coincidentally,

At that moment, Rias was also standing by the window of the old school building, watching Akira leave.

....

After locking eyes for a few seconds, perhaps due to Akira's succubus bloodline at work, Rias was the first to look away.

[Hmm, but in terms of looks, Akira-kun is much stronger than Leisa.]

[It's a pity that demons value strength and bloodlines above all else.]

For demons, strength and bloodlines are their beauty and justice.

.....

Once Rias left the window, Akira finally withdrew his gaze.

Just as he did so, he heard a voice coming from deep within his soul.

[Ding!]

[Detected that you have reached the timeline where the plot begins; system activating...]

[Ding!]

[Congratulations, host! You have activated the "Multiverse Villain Sign-in System."]

[Complete sign-ins or villain events to receive system rewards!]

[System reward levels are divided into five tiers—colorful, gold, silver, purple, and blue.]

[The more difficult the sign-in task, the stronger the sign-in target and higher the rarity, resulting in greater rewards for sign-ins and villain tasks.]

....

Listening to the prompt in his mind, Akira was momentarily stunned.

After regaining his composure,

Akira could only utter one sentence.

"Damn! A system!"

The unexpected event of awakening a golden finger disrupted Akira's original plans.

Now everything had changed; many things needed to be re-planned.

....

The system's notification sound had not yet ended.

While Akira was complaining, the system continued updating its messages.

[Ding!~]

[Congratulations, host! You have triggered a villain sign-in!]

[Sign-in level: Silver.]

[Sign-in type: Event sign-in.]

[Sign-in event: Capture of the Red Dragon Emperor.]

It is well-known that to conquer a world, one must first prevent the original protagonist from gaining an advantage. Therefore, go capture the Red Dragon Emperor's gauntlet!

A journey of a thousand miles begins with a single step; with such an opportunity before him, how could he not seize it?]

...

"Capture of the Red Dragon Emperor?"

"This task..."

Akira looked at the system interface with a troubled expression.

This task was indeed too delicate.

The Red Dragon Emperor's gauntlet... he had already obtained it long ago!

As a reincarnated transmigrator, he had memories from when he was born.

So from very early on, Akira had been planning for the Red Dragon Emperor's gauntlet.

Currently, he possessed it on him.

However, due to his inadequate trading skills with fallen angels, he had only used it once before it became unusable.

[.....]

The system seemed not to have expected that the host could complete the task ahead of time and was stunned for quite a while.

[....]

[Ding!]

[Congratulations! Host has completed the sign-in task!]

[Sign-in level: Silver.]

[Sign-in event: Capture of the Red Dragon Emperor.]

Congratulations! Host has received rewards: Artifact Fusion and Evolution.

Artifact Fusion and Evolution:

Fusion: Perfectly fuse artifacts, eliminate dragon-related weaknesses, erase the consciousness of the Red Dragon Emperor, turning it into an ownerless dragon soul.

Evolution: Completely liberate the dragon soul, allowing it to possess the ability to fuse with other dragon souls and continuously enhance its limits.

Evolution Additional Ability: Artifact Sharing. After evolving an artifact, the host can share the dragon soul for others to use; one dragon soul can be shared with only one person at most.

Note: Only after fully conquering and taking possession of its body and mind can you share an artifact by allowing it to possess your power or bodily fluids.

...

Accompanied by the system's notification sound,

The "Red Dragon Emperor's gauntlet," hidden in a secret space, broke free!

A red light flew out from Akira's embrace and then flew back toward him!

In an instant, the dragon soul merged into Akira's body!

A powerful wave of draconic energy manifested briefly in Kuoh Academy before quickly fading away.

....

Akira did not choose to stay at Kuoh Academy any longer.

After awakening his golden finger, he left Kuoh Academy as quickly as possible.

Then,

At the school gate, Akira saw a black-haired beauty in another school's uniform.

Seemingly sensing Akira's arrival, the black-haired girl ended her leaning against the school gate and broke into a radiant smile.

With an enthusiastic smile on her face, Amano Yuma approached Akira with a slightly shy demeanor.

Seeing this scene, Akira raised an eyebrow.

This person...

He recognized her.

Amano Yuma (Lina Li), is a female intermediate fallen angel stationed in Kuoh Town for fallen angels' side.

In the original plot, she received orders from higher-ups among fallen angels to observe whether there were any special existences around protagonist Issei Hyoudou.

She pretended to confess her feelings to Issei while playing with his emotions from a position of superiority as she toyed with him—a naive virgin boy.

In the end, after losing interest in her game, she dealt Issei a fatal blow.

So now that the plot has changed, why is Amano Yuma approaching him actively?

.....

"Hello, Akira-kun! I am Amano Yuma!"

Amano Yuma closed her eyes and extended her small hand in a shy manner that showed she had mustered up her courage.

Akira admitted that Amano Yuma had a pure aura about her; she exuded an "innocent girlfriend" vibe akin to moonlight shining brightly on white snow.

A boy who has never been in love cannot resist such a beautiful and proactive pure girl like her.

"Miss Amano Yuma, do we know each other?"

Akira genuinely did not know Amano Yuma.

At least in his current setting, he did not know her.

Although he had established cooperation with fallen angels in Kuoh Town, those he collaborated with were Lina Li's close friends—Mitelt (the loli), and Calawarna (the older fallen angel).

He wasn't really familiar with Lina Li at all.

Just after asking this question, Akira heard another prompt from the system.

[Ding!~]

[Congratulations! Host has triggered a villain sign-in!]

[Sign-in level: Purple.]

Sign-in type: Event sign-in.

Sign-in event: Get First Love.

Requirement: Establish a romantic relationship with Lina Li under her alias Amano Yuma.**

[Ding!~]

[Congratulations! Host has triggered another villain sign-in!]

[Sign-in level: Silver.**

Sign-in type: Event sign-in.

Sign-in event: Collect all fallen angels from initial map.

Requirement: Make Lina Li (Amano Yuma), Mitelt (the loli), and Calawarna all your subordinates.**

Note: If you collect them without using violence, your reward level will increase to gold.**