Yuna giggled against his lips, sucking on his tongue before pulling back with a pop. "Mmm. Traveler's so greedy," she purred in her Ganyu voice, but her eyes were pure, mischievous Yuna.
Her fingers trailed through the cum on her stomach. "But big bro..." She licked his cum off her fingertips with a loud moan that was both obscene and arousing.
"...Ganyu really needs her lingerie money by next Friday, you know?"
Suddenly, she grabbed his sticky, softening cock, stroking it slowly. "Or should I tell mom about this?"
Her free hand rubbed his cum into her own pussy. "About how you came all over your little sister while she cosplayed?"
The threat was back, a cold knife in the warm, hazy aftermath. The game, he realized, was never really over.
They lay in the sticky, silent aftermath. Makoto was still panting, the ghost of Yuna's orgasm tingling on his fingertips. Her bare stomach was a canvas for his release.
He needed to put the wall back up, the fragile barrier between what he'd just done and who he'd just done it with.
"I was just kissing and fingering… my Ganyu," he mumbled, turning his head away.
He couldn't look at her, not with her face, flushed and real, framed by that ridiculous blue wig. He was clinging to the roleplay like a life raft.
"And that cosplaying was meh at best, missing the horns, the lens, and the full costume," he pouted.
Yuna sat up, a theatrical gasp escaping her lips as she looked down at her bare chest.
"Meh?! MEH?!" she shrieked, the Ganyu wig sliding sideways.
Her whole vibe changed in a second, from a breathless, satisfied girl to a furious performer. "I gave you a perfect performance!"
She pouted, wiping his cum from her stomach with a finger and then licking it clean while glaring at him.
"This girl is a devil," Makoto thought, a fresh wave of heat shooting through him.
"Fine!" she declared, her eyes sparkling with a familiar, dangerous glint. "If you want horns and a proper costume, that's gonna cost extra."
In one smooth motion, she straddled his waist, grinding her still-wet pussy against his softening cock. The friction sent another jolt through him.
She leaned down, fixing the wig. When she spoke, her voice was a perfect, silky purr. A Ganyu with the soul of a loan shark.
"200,000 yen (~1300$) for the full Ganyu experience," she purred into his ear.
"Complete with bells, horns, and..." Her voice dropped to a sinful whisper. "...letting you fuck Ganyu's tight little pussy."
Her hips rolled against his, a silent, undeniable argument.
"What do you say, dear Traveler?" she moaned, her voice pure Ganyu again. "Want to make a contract with your Ganyu?"
Two hundred thousand yen. The number was insane.
It would cripple him for months. But the image she painted, the full costume, the bells, the raw fantasy of it all, was too much to resist.
He was already screwed.
"Fine, deal," he grunted, his voice rough. He had one condition, one last flimsy shield for his conscience. "But you can't break character while we do it. Or... I'll want a full refund."
"If it's Ganyu, it's not my stepsister," he told himself. It's just a transaction. A performance he was paying for.
Yuna's eyes sparkled. "Deal!" She extended her pinky finger with a mock seriousness that made him want to scream.
"Pinky promise I'll stay in character the whooole time."
She hopped off the bed, striking a demanding pose. "But payment first, dear traveler!"
Her hand shot out, palm up. "Ganyu doesn't work for free, you know! Can't exactly order a cotsume with just your promise."
Then she broke, a wicked grin spreading across her face. It was pure Yuna. "And don't worry, big bro... when I'm in full costume, you won't even remember I'm your stepsis."
She winked, then her expression softened back into Ganyu's smile. "Ganyu will make sure the traveler is... completely satisfied with her services."
With a sigh that felt like it was ripping out his soul, Makoto reached for his phone. "Fine, fine." He opened his banking app, his fingers moving with a grim sense of doom.
"Here goes the savings for my gaming PC upgrade." He cursed in his head.
He transferred 100,000 yen, half of what he had earned from his part-time job over the last few months, to her account.
"Enough? When can I have that Ganyu experience?"
Yuna's phone pinged. She let out a squeal of pure joy. "One hundred?! That's only half!" she pouted, but her eyes were already calculating.
"Fine, I'll take it as a down payment."
She grabbed her phone, her fingers flying across the screen. "It's ordered! The costume should be here in three days with express shipping! And the horns... oh! The bells too!"
She bounced on his bed, her bare breasts jiggling with an enthusiasm that was both contagious and deeply wrong.
Suddenly, she leaned over him, her hair, still sticky with his cum, brushing his chest. "But big bro..." she purred, her voice low, all trace of Ganyu gone.
"If you want the full girlfriend experience, that's another 100k. I'm talking holding hands, cuddling, maybe even..."
She whispered the final, fatal offer into his ear. "...letting you cum inside Ganyu's pussy."
His last shred of resistance turned to dust. "Fine. Friday night, then," he grumbled, pointing at the door.
He needed her out of his room before he agreed to sell a kidney. "Go back to your room. I'm gonna prepare the other half… and maybe book a hotel."
"YAY!" Yuna squealed, skipping to the door. "Friday night it is, dear traveler," she called over her shoulder in a perfect Ganyu voice, blowing him a kiss.
Just before closing the door, she poked her head back in, wiggling her bare ass at him one last time. "Oh! And big bro?"
Her voice dropped to a conspiratorial whisper. "Make sure you book a love hotel with a nice big mirror... Ganyu wants to watch her own face while you fuck her."
She giggled, a wild sound that echoed as she shut the door.
"And no sniffing my panties until then! I'll know if you do!"