Kojima Kana was clearly in a wonderful mood.
To be admired and envied by girls in their prime youth—there was no denying that it was something to be happy about.
After all, she had never been popular with men growing up. And ever since she'd joined the workforce, she'd hidden behind that cold, serious facade—leaving no man brave enough to even approach her.
Perhaps that was exactly why, when she first heard Shirase Haruto was coming from the countryside to board at her place, she'd agreed almost instantly.
Ever since then, she'd worked hard to play the role of the reliable "big sister."
Even if this big sister had zero romantic prospects outside, at home—well, it was her duty to take care of her little brother, wasn't it?
Kana rolled happily back and forth on the couch, her skirt accidentally flipping up to reveal a flash of pink panties.
Shirase was long since used to this sort of thing. He went to the bathroom—and noticed the toilet making a gurgling sound.
He stared at the intermittent trickle of water. After about ten seconds of observation, he reached a conclusion: the toilet seemed to be malfunctioning. Still usable… but barely.
Before bed, Kana mentioned it too, saying she'd call someone over to fix it the next afternoon.
The night passed peacefully.
...
By Sunday afternoon, around one o'clock, Kana left the house after taking a call from Kirisu Mafuyu. With the house empty, Shirase began a new round of [Free Hosting].
Having done this a few times already, he was well-prepared.
He deliberately didn't clean his room, left his English vocabulary book open on the desk, and even made sure his computer screen was parked on a page of historical geography notes.
What he didn't expect was that, the moment [Free Hosting] officially started, he could only watch helplessly as his body rummaged through drawers, found some tools, and then…
…The system controlled him to fix the toilet.
Clearly, this stupid system could do everything except solve math problems.
In under ten minutes, the toilet was perfectly repaired.
But Shirase wasn't allowed to stay home and study—he was marched right out the door.
[Detected potential leakage risk in the toilet. The host lacks the necessary tools. The system has decided to go out and purchase them.]
"But didn't you just test it? I saw it with my own eyes—it's working fine now."
[A wise system must prepare for the unexpected. Preventing potential accidents is the only way to protect the host—lest you consume the Three Holy Fast-Fliers and then suffer through toilet purgatory.]
"Wait—what are the Three Holy Fast-Fliers?" Shirase asked blankly.
[Fried chicken, hamburgers, and barbecue. If the shop uses rancid oil, these delicacies become the Three Holy Fast-Fliers. The host may also refer to this phenomenon as: 'Whopper of Doom.']
Shirase's tone turned strange. "So according to you, if I get scammed by a shady restaurant, next time I'll have to text you something like, 'Disaster alert: man at fried chicken shop—just finished the emergency evacuation'?"
[No need to thank me. Such warnings are part of my duty.]
"…"
Shirase decided to fire back. "Since you know so damn much, how about solving some math problems for me?"
This time, the system fell silent for nearly a full minute before replying:
[When a dog is cornered, it'll jump the wall. When a human is cornered, they can do anything—but math? If you can't do it, you just can't.]
It said this with a ridiculous amount of pride.
What on earth was it so proud of?
"Good thing math happens to be my strong point," Shirase muttered.
As he entered the shopping district in search of a hardware store, the system's notification suddenly chimed again.
[Detected: Person familiar to host nearby.]
[System processing…]
Someone he knew?
Shirase blinked, scanning his limited surroundings. Neither ahead nor to the sides did he see anyone familiar.
Behind me, maybe?
[The person has not approached. System will ignore her.]
Her?
A woman, then?
Shirase frowned slightly. Could it be one of the Nakano sisters?
But he guessed wrong.
The one watching him wasn't a Nakano sister—it was Yukinoshita Yukino.
Across from her sat a beautiful woman with short, stylish hair and flawless makeup.
Her older sister—Yukinoshita Haruno.
The two were seated at a café to Shirase's right, just one table away from the window—close enough that he hadn't noticed them before.
"What are you looking at?" Haruno asked, noticing her sister's gaze fixed outside the window, shifting slightly forward every few seconds.
"Nothing. Just someone I know," Yukino replied calmly. She'd been dragged out for coffee by her sister against her will today.
"Oh?"
The words were casual, but Haruno—who knew everything about her sister's school life—instantly turned her attention toward the window.
She was sharp, and her ability to grasp key details was uncanny.
Within three seconds, her eyes had locked onto the figure of Shirase on the sidewalk.
"That boy? Huh, his side profile's pretty cute."
"You know him too?" Yukino frowned faintly.
"Of course not. But there's no one else around your age nearby, so I assumed that's who you were watching."
"Hmph."
Yukino responded with a faint, ambiguous laugh—but inside, her feelings were complicated.
Still the same as always, she thought. She zeroes in on the truth instantly.
Just how wide was the gap between her and her sister, really?
Yukino, who had always aimed to surpass Haruno, grew increasingly frustrated the longer she thought about it.
Then she heard her sister murmur, "He stopped. Are those stylish people his friends?"
Following her gaze, Yukino saw Shirase standing at the crosswalk, now surrounded by three young men whose appearance could only be described as eccentric.
The one speaking to Shirase had long white middle-parted hair, a nose ring, a selfie stick, and a wrist tattoo plainly visible under his rolled-up sleeve.
"They definitely don't know each other," Yukino said immediately.
Even though she'd only spoken to Shirase once, she heard about him nearly every day at school.
Her insight wasn't as sharp as Haruno's, but it was still enough to judge instantly that those three flashy streamers had nothing to do with him.
"And you're so sure because…?" Haruno's eyes gleamed with curiosity.
Without noticing her sister's expression, Yukino continued, "I happened to meet him once before. And his reputation at school is… peculiar. I've paid some attention since then."
"Oh~? So he's a boy my little sister has been watching?" Haruno's tone turned sing-song.
"If possible, please refrain from using misleading phrasing like that."
"Fufu…"
Haruno chuckled, rising to her feet as she signaled the waiter to bring the check. Then she turned to her sister with a mischievous glint in her eyes. "This is the first time I've heard of you taking interest in a boy. Even Hayama Hayato never earned that privilege. Which means…"
She paused, her smile twisting playfully dark. "Big Sis has decided—I'm going to go meet him."
Yukino's heart dropped instantly.
Oh no. My sister's found a new toy again.
And now she's going to mess with him!