Serafall Leviathan, the only female among the Four Great Satans. A legendary devil who once rivaled Grayfia for her position.
And yet… this overly playful, magical-girl cosplaying woman was somehow the one handling diplomacy for the Underworld. 'Was the Underworld truly safe in her hands?' Kazuki thought.
Serafall continued chatting cheerfully with Rias and Sirzechs, completely unfazed by the stunned reactions of everyone around her.
Although she seemed hurt that Sona hadn't informed her about the open-class day.
Honestly, Sona was probably the one most devastated by this whole scene. Her face had turned crimson with sheer embarrassment.
Serafall, completely oblivious to her little sister's suffering, kept talking with a bright, innocent smile. However, the conversation was entirely one-sided—Sona was practically on the verge of tears.
"I can't take this anymore!"
Finally, Sona's tolerance snapped, and she turned on her heel, bolting from the scene.
"Wait, Sona-chan! Where are you going, leaving your big sis behind?!"
Reacting instantly, Serafall dashed after her fleeing sister.
"Don't follow me!"
"Nooo! Don't abandon me, Sona-chaaan!!"
The rest of the group stood there, half in shock, half in amusement, watching the Sitri sisters' chaotic chase unfold before them.
"Hm. It's good to see the Sitri sisters getting along so well," Lord Gremory commented, completely missing the point.
Inspired by the father's sentiment, Sirzechs attempted to show off his bond with Rias, calling her "Ri-tan" in a playful voice. He was promptly met with Rias' disgusted glare.
Just then—
"I told you not to follow me!"
"Nooo! Don't abandon your big sis, Sona-tan!!"
"Stop calling me '-tan'!!!"
The two sisters had apparently looped around the entire school building, sprinting back into the same hallway, still engaged in their ridiculous chase.
Sona, who was usually the picture of composure and authority, was now completely flushed, teary-eyed, and visibly distressed as she fled. Meanwhile, Serafall seemed to be genuinely enjoying herself, playfully chasing her little sister as if it were some kind of game.
Seeing the look on Sona's face—so similar to the one Rias had earlier—Kazuki felt his irritation bubbling up.
Enough was enough.
Just as Serafall was about to pass in front of him—
"───That's enough!!"
SMAAAACK!!
A sharp, resounding slap echoed through the hallway as Kazuki brought his hand down on Serafall's ass.
"Hyann!?"
A high-pitched yelp burst from Serafall's lips as she leaped into the air, clutching her butt in surprise.
"Huh!? W-What just happened!?"
She spun around, wide-eyed, scanning the area before locking eyes with Kazuki.
"───Did you just do that?"
Kazuki moved in an instant, appearing directly in front of her, his face mere inches from hers.
"Enough of this nonsense, Leviathan-sama!!"
His voice was firm, unwavering, carrying a weight of authority that made even a Maou freeze.
Serafall blinked in shock, taken aback by the sudden scolding.
"You came here as Sona's older sister to attend her class observation, didn't you? Then shouldn't you be dressed appropriately for the occasion?"
"B-But this is my formal attire…~"
"Oh? So you truly believe that dressing like a magical girl is appropriate attire for the guardian of a student council president at a prestigious academy?"
"Ugh! T-That's…"
Kazuki's piercing glare bore into her, making her avert her eyes.
"As the diplomat of the Underworld, you should know better than anyone how to dress according to the situation. But no… You didn't wear this outfit because it was appropriate. You just wanted attention from your little sister, didn't you?"
At his words, her shoulders jolted. Bullseye. Kazuki let out a deep sigh.
"If you keep acting like this, Sona's really going to abandon you, you know?"
"Ehh?! No way! I don't want that!!"
Serafall's eyes welled up with tears as she pleaded desperately.
"Then! You already know what you need to do, don't you?"
"...I-I'll go change."
Her head hung low as she trudged off.
Kazuki scanned the group, looking for someone reliable. "Akeno, can you help Leviathan-sama find something more appropriate to wear?"
"Eh? Ah, yes!"
Just as Akeno stepped forward to assist, a cool voice interrupted.
"Akeno, I'll go."
The one who spoke was a stunning black-haired beauty with glasses—Shinra Tsubaki, the vice president of the student council and Sona's Queen.
"Alright, I'll leave it to you, Shinra-san."
"Understood!! Thank you, Fuwa-kun."
With a slight nod, she led Serafall away. Kazuki exhaled, feeling that at least one crisis was over.
Then, he noticed something.
Everyone was staring at him.
"W-What?"
"Kazuki… You spanked a Demon Lord's ass!"
"Ahhh… Yeah, that might've been a bit much?"
"Of course it was—"
"Not at all! That was a HUGE HELP!!"
Rias had been about to lecture him, but Sona suddenly cut in.
Kazuki barely had time to react before the student council president grabbed both his hands, clutching them tightly. Her delicate fingers were cool to the touch, smooth and elegant.
"Fuwa-kun! Thank you, seriously, thank you!!"
"Uh, well… I did just smack your sister's ass, though!"
"That's completely fine! No, actually, do it as many times as necessary!!"
'Wait. Is Sona okay? Her character seems to be falling apart.' He thought.
"That woman never listens to anything I say! She's a Demon Lord, so nobody else will even try to scold her! I've been suffering because of it, and you actually did something about it… Seriously, thank you, Fuwa-kun!!"
As if overcome with emotion, Sona suddenly hugged him.
"Wha—!?"
The unexpected contact left Kazuki stunned. He looked around for help, but the reactions varied—some were shocked, some were pissed, and others seemed highly entertained.
~~~~~~~~~~~~~~
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