While they made small talk, Yuko’s hand slid boldly underwater. Her fingers found my rock-hard cock immediately and wrapped around the thick cock possessively.

She gave it a firm squeeze, as if claiming what was hers. I felt her jealousy radiating off her in waves.

[He’s been spending so much time with Mom and Aunt Tomiko lately... ignoring me... Well, now it’s my turn. I’ll make him remember who makes him feel the best.] Her jealous thoughts poured clearly into my mind through Telepathy, sharp and filled with competitive heat.

Yuko started stroking me slowly underwater, her grip tight and confident. Her soft palm glided up and down my veiny length while she continued chatting casually with Tomiko, acting completely innocent on the surface.

"Jack has been so busy these days..." Yuko said sweetly, but her hand tightened around my cock in clear punishment. "We haven’t had much time together, right, Jack?"

Before I could answer, her thumb found the swollen, sensitive tip of my cock underwater. She circled it teasingly, rubbing the pad of her thumb right over the slit, pressing and flicking gently. The sudden intense stimulation made me gasp sharply.

"Ah—!" The sound escaped my throat before I could stop it. My cock twitched hard in her hand, leaking pre-cum into the hot spring water.

Tomiko turned her head toward me, concerned. "Jack? Are you okay?"

Yuko smiled sweetly, still rubbing her erect nipples against my arm while her thumb continued tormenting my cockhead underwater in slow, deliberate circles. "He’s fine, Oba-san. The water is just a little hot, right?" She gave my tip another firm rub, squeezing the head between her fingers as if taking sweet revenge.

[That’s right... Gasp for me. You ignored me for so long... do you think I will let my little sister seduce me? If my sister can do it, so can I.] Yuko’s inner voice was dripping with jealous satisfaction as she stroked me faster, her perky tits rubbing harder against my arm, practically humping it with her soft breasts.

Tomiko, still oblivious to what was happening underwater, replied softly, "Yes... It does feel hotter than usual today. My body feels... strangely warm."

Yuko let out a soft, mischievous giggle and pressed her breast even more firmly against me, letting her hard nipple drag back and forth while her hand pumped my throbbing cock with long, sensual strokes. Her thumb kept teasing the sensitive underside of my tip, rubbing in small, wicked circles that made my hips twitch involuntarily.

The contrast was incredibly erotic — Yuko acting all sweet and casual while secretly jerking me off aggressively underwater out of pure jealousy, her soft tits squishing and poking against my arm, while a flustered Tomiko sat on my other side, still tasting my cum from this morning and trying to act normal.

I kept my eyes half-closed, savoring the thick steam and the delicious contrast around me. On the surface, we looked like we were just casually soaking. Underwater, however, things were far more sinful.

My right hand stayed firmly behind Yuko. I squeezed one plump asscheek hard, spreading her soft flesh wide open with my fingers. My middle finger found her tiny, virgin asshole nestled deep between her cheeks.

The puckered little hole was incredibly tight — a perfect, wrinkled pink ring that fluttered nervously against my fingertip, still completely untouched until now. It looked so small and innocent compared to my thick finger, clenching cutely every time the hot onsen water lapped against it.

I circled the sensitive rim slowly, teasing the tight ridges, feeling it twitch and wink under my touch. Yuko’s body trembled against me. Then, without warning, I pressed forward and pushed my middle finger inside her virgin asshole.

"Nngh—!!"

Yuko let out a sharp, muffled cry as her tight ring stretched obscenely around my thick finger.

The heat inside her ass was incredible — scorching hot, silky-smooth, and impossibly tight, like a velvet vice gripping me.

Her virgin walls clenched and rippled wildly around the invading digit as I sank it deeper, knuckle by knuckle, until it was fully buried inside her ass. The muscular ring pulsed and fluttered desperately, trying to push me out while secretly sucking me in deeper.

"Ah—!!" Yuko gasped again, her perky tits bouncing hard against my arm, nipples scraping my skin as her body jerked.

"W-what’s wrong, Yuko?" Tomiko asked again, looking concerned.

Yuko’s voice came out shaky and strained, "N-nothing, Oba-san... the water... just felt a little intense..."

While she tried to speak normally, I slowly pumped my finger in and out of her clenching asshole, feeling every tight ridge and spasm. Her ass was sucking on my finger greedily now, the hot, silky walls gripping me with every thrust.

Yuko’s hand on my cock tightened violently in response, stroking me faster and rougher out of pure overwhelmed lust and jealousy.

After fingering her deeply for a while, I slowly pulled my finger all the way out of her asshole with a lewd, wet schlick. The tight ring clung to my finger desperately before finally releasing it with a tiny gape, closing back up slowly.

I lifted my hand out of the water right in front of Yuko’s face, deliberately showing her my glistening middle finger. It was shiny and coated with her intimate ass juices, the musky scent clearly rising in the steam.

Yuko’s eyes widened in absolute shock. Her face turned deep crimson as she shook her head frantically, silently begging me with wide, panicked eyes.

[No...! Don’t—!! Jack, you pervert—!!] Her thoughts screamed through Telepathy.

I brought the finger closer to my nose and took a long, deliberate sniff, inhaling her virgin ass scent deeply while looking straight into her eyes.

Then, maintaining eye contact, I slid my tongue out and licked her ass juices off my finger slowly, savoring the dirty, intimate taste right in front of her.

Yuko shook her head even harder, biting her lip so hard it turned white, her expression a perfect mix of humiliation, shock, and unwilling arousal. Her thighs squeezed together underwater as a fresh gush of her pussy juices leaked out.

[You’re licking it... You’re actually licking my ass off your finger... right next to Oba-san... I can’t believe you... Why is my pussy throbbing so much right now...!?]