"Y-your..."
"My...?"
"Your butt... I guess..." Kinako's blush grew and she turned away, unable to look Shiki in her large eyes.
"Huh, I would not have guessed that. Well okay, if you insist," Shiki swiftly pulled the waistband to her school uniform's gray skirt and blue panties and lowered the tiny pair of girls towards her rear.
"Wait! No, I don't insist! Aaah!" Kinako panicked.
"You idiot! Why would you choose to be under her ass all day when she's gonna be sitting in class!?" Natsumi barked, pounding her tiny fists against Kinako's body.
"I-I don't know! I panicked!"
"Well great, this is exactly how I wanted to spend my day. I'm not even going to be able to get any good shots squished under her fat butt the whole time..."
"D-don't worry, Natsumi, I'll keep you safe. If anything, I'll probably be the one getting smushed..."
Natsumi rolled her eyes. "Ugh, I can't believe I somehow got myself in this situation..."
Up above, Shiki's cold laughter interrupted their squabble.
"You two sound so funny. Especially at that size. Enjoy your time in there, I'll talk to you both later." With that final sendoff, the hand Kinako and Natsumi were settled on tilted to the side, like a claw machine depositing its prizes. The two tiny idols were dropped into the deep abyss of school idol Shiki Wakana's large ass.
Kinako landed face first on a mass of flesh and bounced off, barely able to keep the tinier Natsumi in her grasp. Natsumi held onto her friend's finger for dear life as the two tumbled down deeper. The brunette bounced between the gigantic mounds of fat a few more times and, after eventually losing momentum, settled between the two cheeks squarely in the center.
"That tickles a bit. Try to play nice in there, you'll have to tell me all about it for my notes later," were the last words spoken by their large friend as Shiki let go of her skirt and panties, snapping the waistbands shut and sealing the two inside for the day.