The atmosphere grew quiet, and the two of them suddenly became reserved.
After her bath, Hashimoto Arina stayed behind in the room to make up the futons for the night. Shirakawa Natsu had offered to help, but she had promptly shooed him out.
He now sat in the recreation room, watching others play table tennis.
It was no surprise that the favorability rating on his phone app still lingered at ninety-nine.
After realizing their bond leaned far more toward sibling affection, he knew that unless he broke through that barrier of "family ties," reaching a full one hundred would be impossible.
"It seems you didn't make it to home base," Miyuki, dressed in a bathrobe, walked over and sat beside him.
"Too many steps were skipped along the way." Shirakawa glanced at her from the corner of his eye. In a yukata, her posture exaggerated her curves—it turned out his "little brother" friend was hiding a rather striking figure.
Leaning back on his hands, he turned his gaze back to the ping-pong table, where the ball bounced furiously under quick volleys.
"I once read this pulp web novel called All My Girlfriends Are Weird," he said idly. "In it, everything seemed so simple—beautiful girls, no guilt, no psychological burden."
"But reality is different. If you keep thinking of someone as your sister, just picturing… going all the way feels like breaking some taboo."
Miyuki narrowed her eyes at him. "So, are you giving up on Hashimoto Arina?"
"Of course not. I'm not some passive anime protagonist." Shirakawa shrugged. "But I do need to get my head straight first. You know, those guys who get off shouting 'sis, sis' or 'mom, mom'—that only works if it's someone else's. In reality, thinking of your own sister like that? It's revolting."
The corner of Miyuki's lips curled into a sly smile. "So, would you rather Hashimoto Arina sleep with the man she truly loves, or with you—while carrying that delicious sense of immorality?"
"Then we'll just share the sin together." Shirakawa answered without a second's hesitation.
"See? That's already psychological preparation. You'll get used to it just by staying close." Miyuki stood, stretching her arms. "I'm off for a massage."
"Massage?" Shirakawa blinked, giving her a quick once-over. In her yukata, she looked more feminine than usual. "From my experience, don't pick some blond, tanned guy to do it for you."
She shot him a look, licking her lips. "I'm the one giving massages."
Shirakawa shrugged. Maybe she should be the one managing the Yellow-Haired APP instead.
He lingered for a while longer, watching the game, but found it dull—nothing compared to watching Hashimoto Arina herself.
Leaving the recreation room, he returned to their quarters. Arina had already laid out the futons on the tatami.
The bedding was spaced half a meter apart. Not too far, but not close enough either. A distance that suggested courtesy rather than intimacy.
Arina stretched under her quilt. Seeing him enter, she smiled faintly and covered a yawn with her hand. "You're back. Go to sleep early—we've got activities tomorrow."
They had traveled for over six hours to reach the hot spring hotel, and after dinner everyone had looked exhausted.
The editor-in-chief, a round man with a booming laugh, had arranged group activities for tomorrow, leaving tonight free for everyone to rest.
"Yeah, I'm tired too." Shirakawa nodded, slipping under his quilt. Ever since that couple's hot spring earlier, the air between them had carried a subtle awkwardness.
Arina got up to switch off the lights. Darkness filled the room.
They could hear each other's breathing, but neither spoke.
He was exhausted, certain he'd fall asleep the instant his head touched the pillow.
Instead, his mind buzzed. Half-asleep, half-awake, he drifted through countless thoughts.
Memories of Arina surfaced one after another.
When had he first begun feeling drawn to her?
At the time, romance hadn't even crossed his mind. She had simply been the attentive doctor who always looked after him.
At first, Shirakawa had only thought of her as a responsible physician.
But gradually, her smile had infected him. Their conversations grew longer, warmer. Slowly, they became friends.
He didn't know how long he drifted in that haze when—whoosh—he heard the faint sound of a quilt being lifted.
Shirakawa's eyes snapped open. His first absurd thought was that he was under attack. He quickly shook it off.
This wasn't one of those shameless light novels he used to read before ending up here. Reality and fiction were worlds apart. Novels let you predict a character's next move from their archetype. Reality didn't care about logic.
Arina stepped quietly to his side, checking if he was asleep.
When he didn't stir, she slipped away, moving softly toward the door. Sliding it open, she squeezed through. Her chest was generous enough that it brushed against the frame as she slipped out.
Shirakawa heard her footsteps fading down the hall. He immediately got up, cracked the door, and followed.
Better to act than lie in bed, wondering what she was up to.
Arina hadn't noticed him trailing her. She passed through the recreation area, heading straight for the hotel's main hall.
There, cushions had been laid out in clusters. Men and women sat chatting in circles, laughter bubbling everywhere.
And among them, Shirakawa instantly spotted a familiar figure. Miyuki—tall, striking, impossible to miss.
Arina walked directly up to her and sat down.
Shirakawa's stomach knotted. Why was she meeting with her?
Not long ago, Miyuki had crossed paths with Yagyū, and now she was with Arina. In between, she'd gone off claiming to give someone a massage. This girl was a master of time management.
The hall was lively, full of chatter. Shirakawa blended into the background, slipping onto a cushion a short distance behind them.
It was enough to fool Arina. Miyuki, though—he was sure she'd spotted him. She simply pretended otherwise.
"He's already asleep," Arina said softly, sitting beside Miyuki. "Is there something you need me to do?"
Miyuki glanced at Shirakawa, then back at her. "Kimura Hama's divorced. What are you going to do about it?"
Arina froze. Shock flashed across her face, giving way to a complicated mix of emotions. "…So he wasn't lying."
"You didn't know?" Miyuki's tone was almost incredulous. "It's hardly a secret among the professors at Tōdai. Anyone paying a little attention would've heard."
Arina lowered her head. "I haven't spoken to him since he came to the hospital looking for me that last time."
"Why?"
"Because… of Natsu." Her voice was small. "I promised to be with him. I didn't want him knowing about Kimura Hama. And… that day, Kimura said the divorce would take time."
At that, Shirakawa's thoughts jolted back to last month, when he and Arina had been walking through the hospital in the evening.
A young nurse had rushed up, saying a handsome man was waiting for her outside. When Arina returned, she'd looked flustered. He had suspected another man, even asked Miyuki to investigate.
"So you're going to hide it from him?" Miyuki pressed. "Treat him like a child, the way you always have?"
"I don't know." Arina buried her face in her hands. "I don't know how to tell him."
"Do you even like him? I mean—like a man, from a woman's perspective."
"…He's still just a boy," Arina whispered. "Like my little brother."
Shirakawa sat silently in the back, absorbing every word. His hands tightened around his phone. He tapped out a quick message to Miyuki.
"In that case, you'd better hurry to Kimura Hama." Miyuki smirked. "He's popular on campus. Wait too long and you'll miss your chance again."
Then, turning serious, she looked at Arina. "But you must be honest with Natsu. Stop dragging it out."
"I…" Arina faltered, her head still low.
"Think about it logically." Miyuki's eyes sharpened. "What's your role? His doctor? His sister? His friend? No matter which, the right thing is to tell him the truth. Then you can chase your own happiness without guilt. So why are you hesitating?"
Arina said nothing.
"You're hesitating because you like him," Miyuki said suddenly.
"No." Arina shook her head firmly. "He's only eighteen. I'm twenty-six. He's just a child."
"In that case, Kimura Hama suits you better." Miyuki's voice dripped with irony. "You care about reason. Kimura is all about reason. You both cling to it—age, position, social roles. Look from any angle, and he's the safer choice."
Still, Arina was silent.
"But people aren't rational," Miyuki went on with a shrug. "A bride swears she'll grow old with her husband, then temptation comes along, and suddenly… photos surface. And what was once a promise…"
"Enough!" Arina cut her off, cheeks burning. "Stop with the twisted metaphors."
"Fine, fine." Miyuki chuckled.
"Just… give me some time." Arina waved her hand weakly. "I don't want to hurt Natsu."
"And how do I know all this about Tōdai's faculty?" Miyuki added with a grin. "Let's just say I'm on good terms with a certain female professor."
"You're about Natsu's age, aren't you?" Arina sighed.
"I'm nineteen."
"Nineteen?" Arina groaned, covering her face. "Great. Outwitted by a girl seven years younger. I'll… I'll think about it."
Regaining a flicker of confidence, she straightened, slipping back into her "big sister" persona, and stood to leave.
As she departed, Miyuki glanced at Shirakawa. "What a sickeningly sweet line."
"Hey." Shirakawa's lips twitched. "You're the one who came up with those twisted metaphors."
"Whatever." Miyuki waved him off.
He let it go. The important part was that a seed had been planted in Arina's heart. Now it was only a matter of whether it would sprout.
Kimura was the rational path.
But Shirakawa Natsu knew—Arina saw him as a younger brother. To win her heart, he had to guide her to realize there was another path.
If that path was taboo, then so be it.
Immorality was only in the mind. It had no bearing on the way their bodies connected.