Sinbi noona had just left.
After that, Sohee said she'd go for a shower first.
Jinwoo sat on the living room sofa, pondering deeply about the answer to the problem Sinbi had left behind.
'0135'
Nothing came to mind immediately.
Sinbi had said that Sohee would get angry if she told Jinwoo, so no matter how much he thought about it, he couldn't figure it out.
Jinwoo was convinced that this number had something to do with dieting.
Then, as the sound of the front door opening rang out, his mom and Minji came back.
"Bro, we're home~"
Minji announced their arrival to Jinwoo.
"Jinwoo, nothing special happened today, right?"
His mom also casually asked Jinwoo as a way of greeting.
Looking at the clock, it was well past 8 PM.
"Yep, nothing special~ Mom, you and Minji are quite late today, huh?"
Jinwoo replied and then thought about things that could be considered 'special': Smacking Aunty Gyuri's ass for the first time.
Witnessing his sister smoking and acting like a delinquent.
Discovering that his sister got a tattoo on the inner part of her thigh.
Apart from these absolutely not-to-be-mentioned special events, there was nothing particularly special.
"Is Sohee still showering?"
Right as they entered, his mom's string of questions continued.
"Yeah~"
And Jinwoo faithfully answered his mom's inquiries.
"Did you eat?"
"I had ramen with my sister."
"Sohee, I asked you to look after your brother's meal and you just make ramen~ I mean, there's rice already made in the rice cooker and side dishes in the fridge that just need to be heated up. What's so hard about that... I'm gonna have to say something to your sister when she comes out."
Even when the person in question wasn't around, Mom's nagging was relentless.
"No, I really enjoyed the ramen... Sometimes you just crave it, you know?"
"Still, you should eat rice when you can~"
Mom was always strict about making sure the kids ate properly.
"But Mom, where did you and Minji go today?"
Jinwoo asked, curious, because it was rare for Mom to take one of the family members out so late.
"We took the day to go on a date, just Minji and me."
Mom said with a playful smile, looking at Minji's face.
"A date? What's that about?"
"Because Mom and I love each other so much~ Hehe."
Minji hugged Mom tightly around the waist and continued with the playful banter.
Mom looked at Minji with a fond expression.
"Yeah, go ahead and get married later, have lots of kids, and live happily!"
Jinwoo joined in the joke.
"I can't have kids since we're the same sex, but I'll adopt you and your siblings and take good care of you."
Minji retorted with a cheeky joke.
"A young stepmom, how creepy."
The silly banter continued, light-hearted and playful.
"Hehehe~"
Minji laughed, clearly enjoying this playful conversation with her brother.
"Mom, did you and Minji eat out?"
Jinwoo asked his mom.
"Yep, we did!"
Mom's succinct reply.
"Dinner is a basic part of a date course~ Ahem!!"
Minji seemed eager to continue the playful conversation with her brother.
"Right~ Did you have a good visit at Gyuri's today?"
Mom petted Minji's head affectionately as she asked Jinwoo.
"Yeah, it went well! The eye mask is in my room, I'll bring it right over."
Jinwoo had received a thank-you text from Aunty Gyuri and since then, he hadn't been too worried about getting scolded by Mom about it.
So now he could answer more calmly.
"Yeah, could you bring it over in a bit?"
Following his mom's request, Jinwoo went straight to his room to grab the shopping bag.
Inside, the light purple silk eye mask Aunty Gyuri had given him was just as it was when he received it.
It could be used as a tool for SM, though that wasn't something easily imagined.
With the shopping bag in hand, he headed back downstairs to the master bedroom.
* * *
As Jinwoo approached the master bedroom, he could hear Minji and Mom talking inside.
"I want to do it now, Mom~"
Minji was pleading with Mom for something.
"No~ Your brother will be down in a moment."
"It'll only take a minute, please, Mom? Mommy~"
Minji whined to her mom.
"Look, we've set a time to do this as promised with your teacher, right? Plus, both you and Mom just got in and haven't showered yet, so let's do it after we've washed up, okay?"
Mom was firm but spoke in a gentle tone to persuade Minji.
"Okay, I got it."
And then came Minji's reluctantly agreeing voice.
Jinwoo couldn't make heads or tails of what they were planning or which teacher they had made promises with, but he thought it best to just play dumb.
"Um.. Hmm.."
Jinwoo made a noise to announce his presence as he entered the master bedroom.
Minji was clinging to Mom, her face buried in her chest like a three-year-old.
Noticing Minji's usually childish behavior seemed more intense today, Jinwoo handed the eye mask to Mom.
"Mom, Aunty Gyuri said to use this well."
"Thanks, Jinwoo. You did well. Oh, and you didn't forget what I asked you yesterday, did you?"
Last night, while Jinwoo was in his underwear, Mom had asked him to be responsible for moving Minji, who often fell asleep in the master bedroom, back to her own room.
Jinwoo couldn't have forgotten Mom's request; he was almost looking forward to it, considering it a bit of a lucky break.
"No, I haven't forgotten. You can go to sleep comfortably now, Mom. I'll come down later and sort everything out."
"That's great, thanks to you, Mom can finally get some good sleep. Then, I have a little favor to ask~"
* * *
Jinwoo left the master bedroom and was heading to his room when he happened to run into his sister Sohee, who had just finished showering.
She was wearing the pink hotpants she had on yesterday morning.
"Did you hear from Mom?"
Sohee abruptly asked Jinwoo.
"About what?"
Jinwoo responded, clueless.
"About Minji."
"What about Minji?"
"Didn't she tell you?"
"What are you talking about?"
Jinwoo hadn't gotten the full story from Mom, so he was hoping he might be able to get it from his sister.
"Hmm~~no, nothing..."
Sohee made a sound like she understood something, then went upstairs.
Her firm thighs and calves were clearly visible as she ascended.
Her enticing backside, wrapped in pink hotpants, swayed tantalizingly with each step.
"What the hell is it?!"
Jinwoo felt a vague sense of discomfort from Sohee's strange response, which was neither dismissive nor condescending.
He felt bitter towards his sister for not candidly sharing the secrets, whether it was about the issues with Mom and Minji or the suspicious activity Sinbi mentioned.
* * *
Back in his room, Jinwoo resolved to somehow uncover his sister's secrets.
'0135'
He wrote down those strange numbers he had heard from Sinbi on a piece of paper and stared at them for a long while.
"An eternal love?"
"Or some area code mix?"
Addition, subtraction, multiplication, division—he wrapped his brain around everything he could think of, but couldn't figure it out.
He felt a burning frustration inside.
It was not a time to hold on to his pride.
Jinwoo wanted to somehow relieve his current frustration and unease.
Without much expectation, he sent a message to Daeho.
'Do you know what '0135' means?'
The reply came quickly.
'What are you talking about out of the blue?'
Jinwoo explained in detail.
From meeting his sister's friends in front of the house to the sisters whispering secrets while eating ramen.
'So Sinbi wrote that on your back?'
'Yes!!'
It seemed Daeho had grasped the situation.
'Wait a sec.'
After Daeho's last message, about 10 seconds passed before the phone rang.
As soon as Jinwoo hit the call button, Daeho's excited voice burst through the smartphone speaker.
"Dude, is this for real?"
"What is it? What's up?"
"You probably won't be able to sleep tonight if you know."
"Stop beating around the bush and tell me, what is it?"
Daeho started to explain slowly.
"First, convert that to digital numbers."
"Okay."
"Then flip it all at once."
"If you flip the '3', it turns into the letter 'E'."
"So, if you flip '0135', wouldn't it be '5E10'?"
"If you change '5' to 'S', it becomes 'SE10'."
"And '10' is the Roman numeral for 'X'."
"Now, what do you see when you combine them?"
"Whoa~!!"
Jinwoo was so shocked that he forgot to speak for a moment.
'S E X'
"Is this for real?"
Jinwoo, utterly astonished, asked Daeho.
"Dude, I wanna ask you—did Sinbi really write this on your back?"
"Yeah, she did."
"So, can I go ahead and fantasize about Sinbi and your sister tonight?"
"Hey maniac, stop it! Your mom is around!! And why are you asking for my permission?"
After a lengthy argument with Daeho, Jinwoo hung up and pondered alone.
'In a world built on sex, what's the harm in a little diet by sex?'
It was the first time he saw Sohee and Sinbi behaving badly.
Until now, they were just his pretty and sexy noonas, nothing more, nothing less.
But from now on, it seemed he would see his noonas in a different light.