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....

Seeing how eager Sona was to try, I handed her the vial.

After opening the vial, Sona drank a portion of my blood. Her expression immediately changed as a wave of pain washed over her.

In the next instant, Sona collapsed to her knees, her body emitting billows of red steam.

"Sona, just hold on a little longer. You'll fuse with it completely soon!" I encouraged her from the side.

Just as I finished speaking, the pained expression on Sona's face vanished, and a powerful Draconic aura emanated from her body.

"How do you feel, Sona?"

"Sona-kaichou, are you alright?"

"Kaichou..."

Seeing this change, the Student Council members gathered around Sona, concern etched on their faces.

"I... I feel much stronger. It's like I've almost reached the level of an Ultimate-class Devil." Sona said, marveling at the changes in her body.

Tsubaki and the others were astonished when they heard their president's words.

Sona, in particular, could clearly feel the powerful presence of the dragon within her.

"Sona, you haven't fully absorbed this power yet. But as time goes on, your strength will increase even faster!" I explained to Sona.

"Yes, I understand, Kyoya. Thank you so much!"

Sona expressed her gratitude to me sincerely.

"Hehe, with our relationship, there's no need for such formality, is there?"

Hearing Sona's thanks—I walked over and gently stroked her smooth, short hair, then teased her.

"Kyoya..." Feeling my hand on her head, even the usually calm and collected Sona blushed.

"Alright, I won't tease you anymore. Next up is Tsubaki. Let's do one at a time!"

....

Then, I had the girls try one by one. I stayed nearby in case anything went wrong.

Thankfully, they all managed to absorb the power successfully, and their strength increased significantly.

The girls immediately decided to spar, saying they wanted to familiarize themselves with their new power.

I watched them fight, a smile tugging at my lips.

Just as I was starting to get bored watching them, a soft, cute voice called out from the distance.

"Sona-chan~~"

Hearing this voice, I looked in the direction it came from. Seeing who it was, I was momentarily stunned. Another familiar character had appeared.

It was a petite, busty beauty.

She looked somewhat similar to Sona, with long, black hair styled in twin-tails that flowed behind her. Strangely, she was wearing a pink magical girl outfit and holding a magical girl wand. What a bizarre individual.

"O-Onee-sama!?"

Seeing this person, Sona's face twitched uncontrollably, and she even stuttered.

It was Serafall Leviathan, Sona's older sister and one of the Four Satans. She was known for her cheerful personality, her love of magical girl outfits, and her extreme sister complex.

As Serafall approached, the system issued a new task.

[Ding! Discovered target character: Serafall. Task Grade: Black. Task Condition: Have her wear the system-rewarded (Exquisite Magical Girl Outfit).]

'I knew it!' I thought to myself. 'That's why the system gave me that magical girl outfit. It was all part of its plan.'

This task was both simple and difficult.

Serafall loved magical girl outfits. If I offered her the Exquisite Magical Girl Outfit, she would definitely accept it.

But Serafall was also an extreme siscon! She had even beaten up anyone who had tried to propose to Sona.

If she found out that Sona was living with me...

'Hiss!!'

Just thinking about it made me shiver!

I needed to come up with a foolproof plan.

While I was thinking, Serafall had already arrived beside everyone and greeted them.

"Yahoo, hello everyone!"

"Onee-sama..."

"Serafall-sama, hello."

"Greetings, Serafall-sama."

"...."

The Student Council members all greeted this Maou.

"Sona-chan, did you miss your Onee-sama? I heard Sona-chan was in danger, so I came right away!"

Serafall said, blinking and making a "V" sign with her hands.

"If I hadn't known my cute Sona-chan was safe, I would have attacked Grigori!"

"!!!"

"Onee-sama, can you please stop saying such terrifying things? It's really causing trouble."

"And I told you, Kokabiel was defeated by Kyoya, so why did you come to the Human world? You're a Maou!"

Serafall's eyes suddenly landed on Kyoya, and she immediately grabbed my hand. "Oh! It's finally nice to meet you! Kyoya, you're little Rias-chan's fiancé, right? Thank you so much for protecting Sona-chan."

"I'm Sona-chan's older sister—one of the Four Great Satans of the Underworld, Serafall Leviathan. If you come to the Underworld, you can mention my name. and no one will dare bully you!"

Serafall said, puffing out her chest proudly.

Hearing this, I was momentarily stunned. Was I about to become a spoiled brat, backed by one of the Four Great Satans of the Underworld? It didn't seem like a bad idea.

"Sona and I are close friends. Protecting her is something I should do. There's no need for thanks."

I just smiled faintly at Serafall's gratitude.

"Hehe, but no matter what, I still have to thank you for saving my sister."

Serafall winked at me, striking a cute pose.

"Also, Sona-chan, you haven't been affectionate with your dear Onee-sama anymore! It makes me so sad! Sniff, sniff..."

Then, Serafall pretended to cry, looking at Sona.

And I finally witnessed the legendary "instant face change."

Tomoe, beside me, whispered, "Kyoya, don't mind it! Serafall-sama is always like this when she sees Sona-kaichou. Just get used to it."

I twitched my lips, not knowing what to say. I could only remain silent.

"Onee-sama, can you please stop being so childish. I'm all grown up now. You've done this so many times. I won't fall for it anymore."

Sona pressed her hand against her sister's head and sighed.

But I raised an eyebrow.

'Sona, you're really something. Aren't you forgetting that you have a slight sister-complex yourself?'

I remembered Sona once saying, "I absolutely won't let my sister come into contact with those harmful pests."

'One is an extreme sis-con, the other a mild one. You really are sisters!' I mused.

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