DxD: I'm Surrounded by Big Sister Devils!

Considering it was Rias's first time, Keikain Fukuki was relatively restrained.

From 3:30 in the afternoon to nearly 5 in the evening, over an hour passed. When the activity in the room finally calmed down, the sky outside had begun to darken, and the streets below were filled with the cheerful chatter of students heading home from club activities.

Back inside, as the movements behind the bed curtain stilled, the heavy breathing gradually subsided.

Inside the bed, Rias, wrapped in nothing but a sheet, leaned quietly against the boy's shoulder, held securely in his embrace. Her dark red hair was damp with sweat from the exertion, and her chest rose and fell with her rhythmic breaths.

Her eyes were half-closed, her finger resting on Fukuki's chest, her lips slightly parted as she exhaled softly.

"Rias."

"…Hmm?"

Fukuki gently called her name, but all he received in response was a faint murmur.

What he considered "restrained" had thoroughly drained the first-timer, leaving her utterly speechless.

The physical evidence within the four-square-meter radius was enough to prove the intensity of the past hour's "aerobic activity."

"Time to wake up. It's getting late," he coaxed, his tone like an adult comforting a child.

"It's almost five. If you don't head back, Akeno and the others might start worrying~"

"…Don't bother me."

This time, Rias's tone carried a hint of complaint. She shifted slightly, adjusting herself into a more comfortable position within his arms.

"I already told Akeno I'd take a walk and that they should eat dinner without waiting for me. Besides, after everything you put me through, I'm so tired… Let's just stay here tonight…"

She trailed off, her voice growing softer, until it became faint and intermittent.

It was clear she was exhausted. Still, Fukuki had one more matter to address.

He gently patted the girl's bare shoulder, lowering his head to whisper in her ear.

"Rias, if you fall asleep now, I'm afraid Miss Grayfia might end up spending the night with us, considering how long she's been standing outside."

"Guh…!"

These words injected the drowsy Rias with a surge of adrenaline. Just a moment ago, she was teetering between dream and reality, but now she sprang into action, delivering a swift knight's kick that sent the dreams she had been indulging in flying, snapping her eyes open.

Right, Grayfia-nee!

Oh no, oh no, oh no…!

In an instant, all her drowsiness evaporated. Rationality overtook instinct as she struggled to sit up.

She couldn't believe her lapse in judgment. After relaxing, she had actually thought about sleeping!

But…well, it wasn't entirely her fault, was it? That guy was just too ruthless. The intense exercise lasting over an hour without any breaks had pushed her to the brink. At first, she managed to hold onto her composure, but by the end, her head felt light and airy, and—ouch~

A sharp ache in her abdominal muscles made her collapse back into the sturdy embrace that held her.

Of course, while Rias felt like she'd been through a whirlwind of thoughts, from Fukuki's perspective, all she did was wriggle a little before plopping back down, like a defiant salted fish.

"If you're out of strength, don't move around," Fukuki said, his gaze filled with fatherly tenderness.

But the next second, the red-haired girl in his arms shot him a fiery glare, half embarrassed and half pouting.

"This is all your fault…"

She didn't even finish her sentence before glaring at him again. This time, the meaning in her eyes was clear—Grayfia-nee is waiting outside right now. What do you plan to do about it?!

What could he do? Of course, he'd just handle it.

Fukuki shrugged, ignoring the startled yelp of the girl in his arms. With a shift of his arms, he adjusted her into a proper sitting position before moving to the edge of the bed and pulling back the curtains.

The room beyond came into view once more. Grayfia still stood gracefully in place, her hands folded neatly in front of her abdomen, her mature and beautiful face showing no discernible expression.

"This should do, right?"

Fukuki tugged the cords, raising the bed curtains at a perfect 45-degree angle. Sitting cross-legged in the center, he had the red-faced Rias, who couldn't even lift her head, perched on his lap.

He repeated himself.

"With this, the engagement should be considered nullified, right?"

"…"

A brief silence followed. Finally, Grayfia, who had maintained a poker face throughout the encounter, let out a soft sigh of exasperation.

"Indeed, at this point, the engagement between the Gremory and Phenex families cannot proceed as planned. However, things aren't as simple as that. Whether the engagement is officially annulled isn't something that can be decided unilaterally just because Miss Rias had…relations with you."

"Fukuki, your relationship with Miss Rias is now a matter of fact. I will report this to Lord Sirzechs and the Phenex family upon my return. How this matter will proceed depends on the Phenex family's stance."

"No problem. I'll wait."

Fukuki's expression remained unchanged, completely devoid of fear.

He raised a finger.

"I only have one demand. If they wish to negotiate, they'd better come prepared to negotiate properly. Of course, if they want to get rough, I don't mind that either."

"But if they try any two-faced underhanded tricks, don't blame me for taking a trip to the underworld myself and reducing the seventy-two pillars by one."

"…"

Despite his brazenly domineering words, the boy exuded no oppressive aura. It was as if he were simply stating an inevitable truth.

Grayfia hesitated for a moment before nodding gracefully.

"Understood. I will relay your words to the Phenex family."

She then turned her gaze to the red-haired girl who had curled up in Fukuki's arms, completely burying her face like an ostrich.

"Goodbye, Miss Rias. I shall take my leave now."

With that, Grayfia turned toward the door, this time not using a teleportation circle. She walked to the door, pressed the handle, and exited without any hesitation.

Outside the room, Akeno Himejima leaned against the wall with her arms crossed over her chest, her head lowered, her bangs obscuring her expression.

The two women passed each other without exchanging a single word.