"W-wait, Nagisa-san, you..."
The Primogenitor girl's explosive declaration utterly shattered Yukina's composure. Throughout this entire chaotic sequence, she'd maintained relative emotional equilibrium—until now.
Did I mishear that? Did she actually suggest...?
"Fufu~ Sounds unbelievable, doesn't it?"
Nagisa shrugged, that perpetually sweet smile never wavering.
"But Nagisa isn't joking."
Oh, so it was a joke after all...
The classic Japanese inverted sentence structure allowed Yukina to catch only "joking"—triggering premature relief.
That relief evaporated instantly the next second.
Wait. What? NOT joking??
"Nagisa means it sincerely."
As if confirming her best friend hadn't misheard, Nagisa repeated the statement with deliberate clarity.
"..."
The sword-maiden's cognitive processes completely froze.
So Nagisa genuinely intends to... uh...
"Difficult to accept immediately, right?"
Nagisa tilted her head, smile unwavering.
"However, this isn't inexplicable. Avrora-chan has explained to both Onii-sama and Yukina-chan about how I became the Fourth Primogenitor, correct?"
The reference targeted Nagisa's biological father's impulsive decision to drag his daughter along on archaeological expeditions. During one such excursion, Black Death Emperor faction remnants had attacked—nearly killing Nagisa through catastrophic injuries.
"After that incident, Mom divorced Dad. Meanwhile, the Fourth Primogenitor's power negatively affected my physical condition. My body became extraordinarily fragile. Even attending normal classes triggered frequent fainting episodes. Mom practically lived in her laboratory—neglecting sleep and meals—desperately working toward separating me from Avrora while eliminating the Fourth Primogenitor power's adverse effects on my physiology."
"But now, thanks to Onii-sama's assistance, I've recovered normal life functionality. However, I can't accept being the only one achieving happiness."
Nagisa paused, lifting her gaze toward the young man before her.
"So I hope Mom can obtain her own happiness too."
"..."
The logic seems... reasonable?
"Mm~ Does this explanation sound excessively sentimental?"
Before either Bokue or Yukina could formulate responses, Nagisa—having just delivered that extended monologue—winked playfully.
"Though for Onii-sama, this shouldn't present any obstacles whatsoever. After all, Lady Venelana and Lady Sheila have already been claimed by Onii-sama..."
Cough cough cough!
The abrupt conversational pivot nearly caused Bokue to choke on his own saliva.
"W-wait! Nagisa, how do you know about Lady Venelana and Lady Sheila??"
"Well, that..."
Nagisa hummed twice, deliberately maintaining suspense.
"Remember when I mastered the teleportation techniques Onii-sama taught me?"
"Ah..."
Brief recollection triggered recognition.
That had occurred during summer vacation—shortly after rescuing Sheila from the demon realm's northern territories. He'd thought he was accompanying Maria clothes shopping. The truth: Sheila had impersonated her daughter. Immediately after their shopping farewell, Nagisa's reverse teleportation array had yanked him to her location.
"Since then, Nagisa has possessed capability to vaguely sense Onii-sama's positional coordinates through teleportation arrays~"
The Primogenitor girl puffed out her modestly-sized chest with evident pride.
"Including those two days in Lilith—one night, I distinctly sensed Onii-sama remaining in Lady Sheila's room for extended duration. Combined with that same evening when Onii-sama accompanied Lady Sheila and Lady Venelana to the night markets... well, what transpired in that room requires no additional explanation, correct?"
"..."
Bokue found himself completely speechless.
So this is the legendary phenomenon where women investigating infidelity achieve Sherlock Holmes-level deductive capabilities.
Even Nagisa—who normally projected sunny cheerfulness toward everyone, apparently unconcerned about anything—demonstrated extraordinary analytical prowess in this particular domain. Beyond innate talent, no alternative explanations existed.
"Hehe, regardless—this constitutes Nagisa's request for Onii-sama~"
Ignoring the completely dumbfounded sword-maiden nearby, Nagisa leaned forward once more—breath tickling his ear with humid warmth.
"Mom's attitude today was abundantly transparent. Perhaps when I accompany Onii-sama to Mom's laboratory, she'll exploit equipment examination intervals to... mm, Onii-sama must seize that opportunity properly. Just like with Lady Venelana and Lady Sheila..."
"Oh right! Speaking of which, has Onii-sama's interest been piqued already? Come to think of it, Yukina-chan mentioned we could visit Mom's facility this afternoon for examinations. Originally, Nagisa felt lazy about leaving the apartment, but now sudden motivation has emerged."
"How about... departing immediately after lunch?"
The girl's voice grew increasingly intimate, concluding with her lips brushing against his earlobe.
"Perfect timing—Mom takes lunch breaks with rest periods afterward. Plus, the lounge connected to Mom's office contains an enormous, incredibly soft bed~"
Nagisa's persuasion carried seductive undertones.
❁❁❁❁
Simultaneously, elsewhere—having departed the apartment and performed superficial cleanup with napkin application—Mimori finally reached her research facility.
Sunday meant complete facility vacancy except herself.
She parked with maximum efficiency, ascending via elevator to her office floor. Upon entry, shoes were immediately kicked aside before she pivoted directly toward the "lounge."
This so-called lounge actually constituted a luxury suite rivaling premium hotels—originally designated for high-priority patient recuperation, enabling immediate physician contact during condition changes.
However, after Mimori's office relocation here, she'd commandeered the entire suite as personal research facility quarters. It had effectively become her secondary residence.
Mimori traversed the suite's living area and corridor, entering the bedroom. Her hasty pace dislodged the napkin—it fluttered through air, revealing conspicuous moisture stains saturating the fabric.
But she couldn't spare attention for such details. The bedroom's attached bathroom door was pushed open. She stepped inside, sealing herself within.
Moments later, bathroom illumination activated. Shower water began cascading. A feminine silhouette pressed against frosted glass, accompanied by breathy murmurs.
"Nagisa, forgive me... Mom has already... mm..."
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