"Damn that Yin!" 

A tall woman with long dark hair stomps across the dimly lit room throwing her white masquerade mask and a brown bag roughly on the metal table. The woman is clad in a very form-fitting white leather suit that left very little to the imagination. She begins stripping out of the stuffy outfit to change into something more comfortable.

"What the is their problem, Seulgi?!"

A slightly shorter girl had been following the mysterious woman picking up any of the items and clothes she dropped behind as she headed straight for a closet for a change of clothes.

"I don't know, Joy."

"That bastard had the gall to not only handcuff me to a pole, but they also replaced the jewel with a fake and stupid sarcastic letter."

Seulgi searched the brown bag and found a note. She read it aloud. "Ms. Yang, You are already more beautiful than any jewel. So I'll be taking the Atlantis Eye. Please do tell the police chief I said hi." 

By the time Seulgi finished reading the note, Joy had swapped her sticky flashy outfit for grey sweatpants and a white t-shirt.

"They seem greasy…"

"I don't get it Seulgi, how are they always a step ahead of us?" Joy wanders upstairs to a modest house and turns on the news knowing the media will have something to say about her latest escapade.

"The Yin and Yang Thieves once again responded to Ms. Kim's challenge and have come out on top once again."

"We aren't on the same team!" Joy yelled at the TV like a disgruntled sports fan.

"Despite the efforts of over a thousand police officers and the latest in security technology. They proved useless once again against the Yin and Yang Thieves. Through the use of clever teamwork and flashy distractions, they captivated the audience while also accomplishing their goal. Once the dust settled, they had gotten their hands on the Atlantis Eye and escaped police custody."

"Ah, this is so stupid! We should be filthy rich right now, instead, we are barely scraping by because of that jackass Yin."

Joy didn't love the nickname Yang as it connected her to her rival, it made it much simpler to have a name to curse out.

"I know I've asked this a hundred times before, by why do we stay in this city? New York, Hong Kong, London, all perfectly, easy, non-Yin containing cities we can set up camp in." Seulgi takes a seat right next to Joy, but Joy stands right back up, walking towards a window.

Joy looks out and the view isn't grand. She sees a street with cars lazily parked and kids denting said cars as they play with their ball on the street. This view of a suburban street was supposed to be a view overlooking the vast city already.

"Then Yin wins Seulgi. Besides, no other city has Yerim Kim, whose ability to collect priceless gems and then stupidly risk losing it for a challenge bares no rivals."

"I get that, but you three have practically created a comic book city. Our city currently has a 3:1 civilian to police ratio. This is your playground more than it is a functioning city…"

"Whatever, let's start preparing for the next challenge, Yerim won't stop now."

"Wow, she was absolutely stunning today."

A much shorter girl than Joy placed an identical brown bag next to a big pile of clothes.

"When are you going to stop messing with her and actually get her arrested?"

"Why would I do that? She hasn't actually stolen anything."

"Yeah! Because you always take it from her! She is still breaking the law, Wendy!"

"Yah, yah, whatever."

A girl of similar height to Wendy ruffled her hair in frustration from her friend, the illustrious 'Yin'. 

Yang sought out the spotlight. She encapsulated this idea with a flashy, white, form-fitting ensemble and her willingness to interact with the public in the form of grand speeches. Yin, on the other hand, worked from the shadows. Her outfit of choice was black and formless. The flashiest thing about her was the helmet she used to keep her completely discreet.

"Irene, can you ensure the Eye goes back to the village?"

"I've already set up a secured delivery."

"Good."

Wendy slowly waded through the hung up clothes to a sofa hidden in the back.

"Ugh, Irene. Do we really need to actually run this shop? It gets in the way."

"I need a hobby in between challenges." Irene shrugs.

Wendy tries to slowly lower herself onto the sofa, but her body gives out dropping hard. She lets out a rather loud cry which springs Irene into action.

"You're hurt!"

"Hmm maybe?" Wendy could only manage a raspy response as her abdomen throbbed in pain.

"What happened? You are usually so careful." Irene began inspecting the damage.

Irene didn't expect the few moments of silence. Wendy was looking in a random direction, avoiding the topic.

"It was Yang, wasn't it? Let me guess, she doesn't even know you saved her life?"

"Saved her life is a little strong…" Wendy tried to adjust her position which was only accomplished through a bunch of pain.

"She is going to get you killed. She is a common thief. Why do you go to such lengths?"

"Call me a romantic, but I think she has a good heart."

"I guess I've seen people call them a 'heart'." Irene stood up to sit next to Wendy.

"Hey! I'm being serious!"

Irene simply waved her off.

"So what are you going to do?"

"The only thing I can do, keep whittling down Yerim's empire."

"It's amazing that no one is suspicious of how she gets all of these priceless gems."

"I wish we could do more, but this is to the extent of my abilities and by the time money reaches Yerim's pockets, they are clean."

"You are doing a lot already." Irene grabbed her hand. "If only you didn't have Yang slowing you down."

Wendy laughed but was stopped abruptly by her injury. "Yeah, but she keeps it fun. Feels less like work."

"You're an idiot."

"An adorable idiot, right?" Wendy gave puppy dog eyes to Irene.

"Just an idiot." Wendy pouted. "So when do you think the next challenge will pop up?"

"Well, Yerim's next project is already halfway finished. She is speeding up her pace."

"Are you going to be healthy by then?"

"I think it's only a few bruised ribs, a few weeks and I'll be fine."

"Alright." Irene got back up and headed back to the front of the store. "Just remember you are important to a lot of people. I'm sure Yang might be a nice person, but you need to watch out for yourself too."

"Yerim, you need to stop pushing these challenges!" The decorated police chief paced back and forth in the fancy office.

"Eyy, you worry too much Taeyeon!"

"We haven't stopped them a single time! How can you even afford all of this? You even tripled the police force!"

It was quite a mystery to everyone except Yerim and her bank. The short answer was, she couldn't. Dirty business strategies worked wonders as she never had to lift a finger once all of her systems of checks and balances were in place. It came to the point where she needed a hobby.

"Don't worry about that my dear, just keeps thinking of new ways to stop them next time!" Yeri spun around in her chair like a child.

That new hobby, the most expensive hobby in the world was challenging to master thieves to a game of cat and mouse. 

"We've tried everything… You've challenged them 220 times and haven't kept your treasure ONCE!"

It all started with Yerim dipping her toes into running an art gallery for the top influencers in the world. She was promptly made to look like a fool as Yin and Yang crashed her party and stole every painting being showcased. She was humiliated, but motivated.

"They 221 must be my lucky charm!"

"How are you so optimistic?"

"It's less about the results and more about it being fun. Isn't the clash of minds a fantastic sport?"

Yerim puts on the classic villain laugh as she stands up and glares out her giant window.

"Come come, Taeyeon, I have something to show you."

Taeyeon walks over tentatively as Yeri creepily waves her closer. Yeri pulls her in close and shows her a view. There is construction going on right outside of her office.

"This is my masterpiece, it will be done in two months time. It will be my most grand building yet, the building to end the legend that is the Yin and Yang thieves."

As two months sped by, there was no official challenge issued yet, but Yin and Yang weren't good at their profession by playing passively. They took advantage of weaknesses during the development period, before Yerim took in any real interest in the project. This meant collecting blueprints and even setting up potential weak spots before the building was even finished. The first plan was more of Yang's wheelhouse. Seulgi was capable of gathering any information stored on a PC, even easier if connected to the internet, which most computers nowadays were. The blueprints were obtained rather easily. Yin, on the other hand, was much more low tech. She visited the construction site and observed the building while only its skeleton existed. Watching the build progress from the beginning gave Wendy an advantage when creating a plan of attack.

Once the building was finished, exploitable weaknesses disappeared as Yerim finally got involved. Early on, Yerim relied on standard security systems that stood no chance against Seulgi's expertise and Yin's experience. It was when Yerim started including experimental systems did things become complicated. Some of the systems they had to crack included a DNA scanner that only took Yerim's blood, a teleportation system that hid the gem when it sensed a presence, and even a time machine that reverted time back an hour whenever the gem was stolen. Of course, the more experimental and complex the machines were, the more oversights were found, like the fact that a time machine requires more energy than the city can even produce. This time around, Yerim went simple, back to standard security systems, and it surprised the two thieves.

"Wendy, you're still hurt, you don't have to do this."

"I'm fine…" Wendy stretched her abdomen. She was able to hold in any yelps of pain, but groans of soreness couldn't be contained.

Irene stared at Wendy as she handed off parts of her outfit.

"Look, I'm fine." Wendy steps back to do a backflip. Irene always forgets this girl is extremely gifted in the athletic department.

"Why are you even accepting this challenge? Yerim doesn't seem to be trying and she is actually putting her own jewels on the line, there isn't anything for you to steal."

"Don't you think Yang will be there? Who are the Yin and Yang thieves with Yin?"

"Are you really doing this for that woman? You are hurt!"

"Irene, thank you for everything. But I h