The external differences were noted. For the sake of the "test," it was time to check the internal differences.
"For the test"—it was a transparent excuse. Yotsuba, who wanted to stay with her sisters through sports, and Miku, who wanted to be with the man she loved without losing her family, both knew it. But it was Rin's excuse, and it was theirs too.
"How... how are you going to check?" Yotsuba bit her lip, her blue eyes wide with anticipation. Unlike Miku, Yotsuba had an extra reason to go along with this. Because she was athletic, her libido was naturally higher. She masturbated in her room much more often than her sisters. If Rin's fingers felt that good, what would more feel like?
"Sit on the edge of the bed... yes, spread your legs."
Under Rin's guidance, Miku and Yotsuba sat side-by-side in an "M-shaped" leg spread. Their heat and dampness were fully exposed. The two girls had no secrets left; every inch of their intimacy was laid bare for Rin's eyes.
"Aside from the level of moisture, they look identical. The hair is just a little patch. The important parts are smooth."
Even though they were getting used to his touch, his clinical evaluation made them die of shame.
"Don't... don't say those things out loud." "Um... this pose... is very embarrassing."
Yotsuba whispered her impatience. When he had been playing with her breasts, she was already reaching her limit. Miku was so flushed her eyes were watery. The cool air from the air conditioner made them shiver, but Rin's intense gaze felt like it was burning them.
Seeing Yotsuba couldn't wait any longer, Rin stopped talking. He reached out with both hands and pressed his fingers against their folds.
"Ah!!!" "Ngh!!!"
Cries escaped their lips. It wasn't their first time being fingered by him, but doing it in this pose, side-by-side, was incredibly erotic. Since they were both virgins, Rin was careful. He slid his fingers in just a little, feeling the resistance of their purity.
"The internal differences are much larger than the external. Yotsuba, you're much hotter inside, and much wetter."
Hearing that Yotsuba was "better" in some way made Miku pout. She stubbornly squeezed her internal muscles. Rin laughed at her jealousy.
"But Miku, you're much softer inside. The way you wrap around my finger is tighter..."
"Hmph..." Miku's lips curled into a tiny smile of victory, but she quickly covered her mouth with her hands as she gasped.
Last time, Rin had been kissing them and teasing them. This time, they were wide open. A simple hook of his finger sent jolts through their entire bodies. Their waists arched and buckled, their toes curled, and their moans filled the room. Rin's fingers explored every sensitive inch, leaving no spot untouched.
Outside the door, Nino and Itsuki were bright red.
The soundproofing was good, but Nino's room was right next door. Itsuki's room was the furthest away, but Miku and Yotsuba weren't being quiet. They both stood in the hallway, drawn by the sounds.
"Honestly... what are they doing!?" Nino crossed her arms, looking annoyed. "He hasn't even passed the test yet..."
"Ahaha... haha..." Itsuki laughed awkwardly. "Should we go tell them to be quiet?"
"You want to go in there?" Nino glanced at Itsuki's red face.
"N-never mind. Too awkward. I... I have earplugs. Do you want some?"
"Yeah... give me two."
The moans didn't last much longer. After ten minutes, the loud cries turned into heavy, wet panting that didn't carry past the door.
"Hah... hah..." "Ngh..."
The two girls lay collapsed on the bed, drenched in sweat. Their heavy breasts heaved with their breath, and their M-shaped legs had fallen open weakly. Rin reached out and wiped the fluids from his hand onto their lips, making them taste their own juices. They were too spent to resist his wicked sense of humor.
Finally, Miku and Yotsuba regained their senses. Their eyes fell on Rin. Even through his loose shorts, his excitement was impossible to hide.
"You two are finished... now it's my turn."
Rin sat on the edge of the bed. Miku and Yotsuba knelt on the carpet between his legs, getting their first close-up look at a fully aroused man.
"It's late, and you have school tomorrow. Today, I'll just teach you how to serve."
He wasn't going to "eat" them just yet. A five-twin harem was something he'd only seen in doujinshi. He didn't want to waste such a rare opportunity. He imagined them all lined up on the sofa, asses in the air—Ichika, Nino, Miku, Yotsuba, Itsuki...
God...
The thought alone made him throb. For now, a little "training" would do. Rin looked at the two dazed girls. He gently took their wrists and guided their hands toward him.
"Ah!!"
Yotsuba let out a tiny gasp when she touched him. Miku tucked a stray hair behind her ear and reached out cautiously. The moment she felt the heat, she flinched back as if she'd touched boiling water, but then, holding her breath, she reached out again.
"First, the basics: your hands. If it's not slick enough, use some spit... either yours or mine."
Rin began his lecture. The two girls watched like star pupils. If only they were this focused on their schoolwork.
"Besides your hands, you can use your breasts. Alone, you slide it between them. Together, you stand on either side... the physical sensation is the same, but the psychological feeling of conquest is doubled."
"And then, there's your mouth. Like eating an ice pop. But be careful not to use your teeth. Look up at me while you do it."
"Of course... you can combine all three."
Miku had some theory, and Yotsuba had almost none, but after ten minutes of instruction, they understood the basics. Just as Rin was about to let them practice, Miku called for a timeout.
"Wait... wait a second."
Rin and Yotsuba looked at her. Was she too shy? Did she not understand?
Miku scrambled over to Rin's suitcase and grabbed one of the square, foil-wrapped condoms Kaede had packed.
"Huh? We don't need those yet, do we?" Yotsuba tilted her head. They'd seen condoms in health class—some boys had even blown them up like balloons. They knew what they were for. But for hands and mouths? You can't get pregnant from that.
"It's... just in case it gets messy. It's hard to clean up," Miku said, looking away guiltily. In truth, Miku used to think they were just for birth control... until that day Ichika took her to the wardrobe to watch Rin's "party" with the other girls. She had seen Suzu demonstrate that condoms had other uses.
Besides, Ichika was his official girlfriend. If he was "serving" Miku and Yotsuba, it was technically cheating... and that made it even more perfect.