(Credits to the uploaders and also to the people sharing the videos)
*Nail Salon Paris Workers:
Park GyuRi as Hong Yeo Joo (25)
She's a fantasy (gumiho related) online /internet novelist/writer.
Growing up without a mother, she lived in a countryside with her dad when she was young.
She's very smart, outspoken and confident but lacks real life romance/dating experience as she is stuck in her room most of the time with her computer.
An issue arises when a case of plagiarism appears. The accusation bruises Yeo Joo's pride and she tries to create a new novel because she doesn't want to be accused again as a copycat and quit as a writer.
One day Yeo Joo sees Alex encountering a dangerous situation like a modern day hero and interested in the hero, she decides to trail him and finds that he's a nail salon specialist. Wanting to write a new novel using him as material , she decides to cross dress and get a job at the Nail Salon Paris. As a guy, her name is Hong Ki Joo and nicknamed as Ba Ni (Bunny).
Song Jae Rim as Kang Jong Hyeok, age 27, his nickname is Kei /Kay ( K ).
He's is second eldest of the three nail specialist / artist of Nail Shop Paris. With a masculine image, he has a strong sense of justice and is known to keep a cool visage in front of customers, earning him the title "ice prince". With his strong sense of justice he has a tendency to act before he thinks and this ends up working against him as the situation usually gets worse. This leads to conflicts between him and Alex, who is more thoughtful.
As an artist and art student, he has a sharp eye and is considered the best nail artist in the shop. Originally disliking the idea of having Ba Ni work in the shop due to Ba Ni's suspicious behavior and "his" feminine looks but K ends up finding his heart beating at the sight of Ba Ni. "
Jeon Ji Hoo as Kim Ji Heon, his nickname is Alex , age 28.
He's the eldest of the three nail specialist / nail artist of Nail Shop Paris.
He's intelligent, sweet guy with handsome looks and a caring personality.
He used to practice traditional medicine but after hurting a patient he gave it up due to his guilt.
In the nail shop, he is like an elder brother and mediates the conflict between others.
He and K have a brother-like relationship and due to their different personalities, they fight at times.
K is more expressive with emotions and Alex is usually calm and reserved, but their relationship is one of mutual acceptance and understanding.
He also watches over Ba Ni/Yeo Joo as she is begins her training and helps her when she makes mistakes due to a clumsy nature. In addition, he praises Ba Ni's sense of color and design.
Met with a misunderstanding surrounding a beautiful woman president, Alex believes he's in love but has never admitted it to her.
(Additional Info (Yeo Joo,K &Alex) Source : buinn of AKP , Thanks also to @uglypearl who shared the additional character information to this forum)
Park Sang Hyun (Cheondoong, 23) - Member of MBLAQ ; Acted in drama Padam Padam (JTBC/ 2012)
He plays Jin , Paris' maknae (youngest) of the three flower boy nail specialist / nail artist of Nail Shop Paris .
A person full of aegyo (cuteness) and has a very sociable personality.
A very cheerful person also the atmosphere maker in Paris, he is one of the people that receives lots of love.
Growing up without a father, he was brought up by his mother who works as a medium.