The old apartment building gave off a faint scent of mold. The stairs leading to the second floor were rusted from years of rain, and every step from the staircase to the corridor was accompanied by a soft, rhythmic creak.
With the turn of a key, an ear-grating screech echoed in the hallway.
"...Why are you all looking at me like that?"
The moment Rin entered the apartment, he saw them all staring at him intently. As expected of the four sisters—they had come up with a "bad idea" remarkably fast.
Tonight, Rin had come over to supervise their studies, not expecting that after Kaede declared war this morning, they would have a counter-strategy ready by the afternoon.
"Sitting here and not studying... what's going on?"
Rin's eyes swept across the girls, subtly testing the waters. Nino, however, didn't hide anything and spoke directly.
"I asked Nijika and Ryo to help satisfy Ichika's cuckold fetish. But none of us have any experience... so you need to figure something out."
Nino's embarrassed expression made Rin burst out laughing. What intrigued him more was Nijika's involvement.
"You actually agreed to this?"
Nijika was a gentle little angel, not a seductive succubus. Moreover, she was still a virgin—how could she agree to such a depraved scheme?
"Uh..." Nijika lowered her blushing face, her cheeks twitching with awkwardness. She had indeed wanted to refuse, but after Ryo's relentless pestering, she had somehow ended up agreeing—and for free, no less.
Rin sat down on the tatami and got a brief rundown of the situation. Simply put, after hearing Kaede's provocations, Nino felt Ichika needed a sense of crisis regarding her man being "stolen," so she recruited Ryo and Nijika. However, they lacked the experience to pull off a convincing "affair" and had to turn to Rin for help.
Yotsuba poked Rin's arm with a grin. "Hee-hee, don't you draw those 'Reverse NTR' doujins all the time? Quick, give us a plan."
"To give Ichika a real crisis, a standard affair isn't enough..." Rin mused for a moment before looking at the sisters. "In stories like this, there's usually an element of coercion. Does Ichika have any secrets or weaknesses? Something that, if caught, would make her say, 'I'll do anything'?"
"I don't think so?" Itsuki tilted her head toward her sisters. "Do we have any shameful secrets?"
Nino and Yotsuba frowned as they tried to remember, but both shook their heads. Miku, however, stared at Rin for a while before speaking.
"The fact that all five of us are with him is our biggest secret... Ryo, your father runs a private hospital, right? Maybe your father and our father know each other."
"How would I know if they know each other?" Ryo replied.
Nino and Miku shared a glance, instantly understanding Miku's angle.
"It doesn't matter if they actually know each other. As long as Ichika believes they do! You just use that to blackmail her! Make her stand guard or clean up for you while you're with him..."
Just as the four sisters were reaching a consensus, Rin raised an objection.
"Blackmailing her your way won't work. Ichika could easily turn it around and threaten Ryo—threatening to tell Ryo's father about all this."
"So..."
Nino and the others, along with Ryo, followed Rin's gaze and landed it squarely on Nijika.
Facing their stares, Nijika froze for a moment, then pointed a finger at herself blankly.
"Me...?"
9:00 PM.
"I'm back... Eh? You guys haven't gone home yet?"
When Ichika returned to the apartment, she was surprised to find her four sisters still on the tatami. Usually, after tutoring ended around 8:00 PM, Nino and the others would leave with Nanami and Rin.
Wait...
What was going on today? It wasn't just that they were still there; none of them were on their phones or studying. They were just sitting there with incredibly somber expressions.
"What's wrong?"
Instead of answering, Nino and the others pointed toward Ichika's bedroom.
???
Ichika walked slowly toward the door and opened it in confusion.
"...?"
The scene before her made her jaw drop.
Inside the room, a naked Rin was tied to a chair. Nijika was standing in front of him, one foot stepped up on the edge of the chair between his legs. Her white-socked toes were pressed firmly against Rin's crotch.
A pair of what looked like Ryo's black pantyhose was stuffed into Rin's mouth. Seeing Ichika, he couldn't speak, only letting out muffled "Mmmph! Mmmph!" sounds.
On the bed nearby lay Ryo, also tied up, with her own pantyhose stuffed into her mouth.
Nijika, usually the "Angel" of the group, was scowling with a look of intense fury.
"Uh..." Before Ichika could say a word, she was dragged back into the living room by her sisters. Miku, being the last one out, didn't close the door fully, leaving a small crack.
"Don't disturb them!" Yotsuba made a shushing gesture. "If Nijika gets even angrier, it's all over!"
"Huh?"
Facing a bewildered Ichika, Miku and Itsuki guiltily looked away. Nino glared at them—they had agreed to speak together, but now they were dumping it all on her!
Fine. Itsuki was a bad actress anyway; she'd probably blow their cover. Nino sighed and began her scripted lines.
"Ichika, here's the thing... You know Ryo and Nijika come back late because of their part-time jobs and band practice. So... we decided to have a small party here with him. They walked in on us. And... Nijika and Ryo actually love him too..."
"And...?" Ichika was confused. She had already guessed there was something between Rin and the band girls. If they walked in on it, so be it—why this drama?
"They aren't like Nanami or Mashiro!" Yotsuba added in a hushed voice. "They loved him from a distance. They didn't know he was such a perverted playboy who was seeing all of us!"
"Yeah." Nino nodded, keeping her voice low. "They were going to give up when they found out he was your boyfriend. But today, they caught us all together. They know the truth about the five of us now."
"Nijika is furious." Miku patted her chest as if still frightened. "She said, 'You wouldn't want your father to find out about this, would you?'"
"This..."
Listening to the fabricated story, Ichika's mind built a narrative of a pure-hearted girl going dark. Nijika, who had hidden her love, had snapped upon seeing the "party." Now, she was blackmailed the sisters into silence by threatening to reveal their scandalous relationship to their father.
"How does she know Dad?" Ichika asked.
"Ryo's father has a private hospital. Nijika has met him. Ryo's father knows our father," Nino said, quickly adding, "We absolutely cannot let Dad find out!!!"
Miku nodded seriously. "Nijika is in a blind rage right now. She even tied up Ryo. Let her cool off while Rin 'explains' things to her... Don't interfere, or she might call Dad right now."
While the five sisters stayed in the living room, inside the bedroom, Nijika was staring blankly at the hard cock twitching beneath her foot. Her heart was racing faster than it ever had on stage.
Even through her white cotton socks, she could feel the incredible heat of his dick. This was the most intimate contact she'd ever had with him—the last time was just a kiss, but now she was stepping on his manhood.
Rin blinked at her, and then...
"MMMPH! MMMPH! MMMPH!"
Rin let out loud, muffled groans. In the living room, the four sisters looked at each other—that was the signal!
Yotsuba pointed at the door, and she and Ichika crept over to peek through the crack.
Through the gap, Ichika saw Nijika's foot pressing into Rin's crotch. The contrast was stark—Nijika's small, socked foot was dwarfed by the massive erection Rin was sporting.
"Pervert... pervert! You really are a cheating pervert! Your girlfriend is right outside, yet you get hard just from me stepping on you. You're the kind of pig who gets excited for any woman, aren't you?"
Nijika stumbled through her lines. This was far too embarrassing for her; her cheeks were so red they looked ready to bleed.
Rin had convinced her to do this by calling it "stress relief." After their first kiss, Nijika had started masturbating in her room to relieve tension. Rin had told her this would be even more effective.
But is this really relaxing? Nijika felt more stressed than ever.