K-Drama couples who start off with a senior-junior relationship

 emaureeng:

Not sure what this means. Older and younger?

No. One of them joins before in the workplace and is like a "mentor" to the other in the workplace..

Start with a junior-senior relationship:

• Go Ho's Starry Night - The ML is a team leader and was the FL's senior / mentor at work for years, but at the beginning of the drama the FL is transferred to the other team that works in the same office space so she is no longer his direct junior. 
• The Secret Life of My Secretary - The ML is... some kind of senior executive? I don't remember his exact title. As the title suggests, the FL is his secretary.
• A Poem a Day - The FL is a physiotherapist working as part of a hospital team on a temporary contract. She is the most junior member of the team. The ML is a doctor who joins the hospital as the most senior member of the team.
• Cheese in the Trap - The ML and FL are top students at the same university and sort of rivals. The FL refers to the ML as sunbae. 
• Ms. Perfect - The ML is a lawyer and the FL is something like a paralegal.
• Suspicious Partner - The ML is a prosecutor. The FL is a junior lawyer who ends up working with him.
• You're Beautiful - The FL joins the ML's boy band / k-pop group as it's newest member.
• Strongest Deliveryman - The ML and FL are both experienced food delivery workers, but the FL has worked at the same place for several years while the ML moves from job to job. So he joins the FL's restaurant as her junior.
• Jealousy Incarnate - The ML is a news anchor. The FL is a weather girl at the same station who dreams of becoming an anchor. However, they don't interact very much through their work.

Have a junior-senior relationship or a junior-boss relationship, but not from the very beginning:

• Healer - The ML is a man for hire. He is hired to watch / protect the FL but becomes curious about her. He goes under cover as a timid new hire at the FL's workplace where he becomes her direct junior.
• Her Private Life - The ML and FL meet before working together, but within in the first episode or two (it's been a while since I watched so I don't remember the exact timing) the ML becomes the director of the art gallery where the FL works.
• Love in the Moonlight - Circumstances lead the FL to enter the palace while pretending to be a eunuch. She ends up becoming the primary eunuch to serve the crown prince (the ML). The ML and FL met several times before the FL becomes the ML's personal eunuch, and the ML is largely responsible for that outcome.
• Coffee Prince - The ML hires the FL to work at his coffee shop. They met a few times beforehand.
• My Secret Romance - The ML is a CEO and the FL is a nutritionist hired to work at his company. Due to his dietary restrictions, she is tasked with personally planning and preparing the ML's meals. The ML and FL met in the past years before the FL was hired at the ML's company.  
• Hotel del Luna - The FL wanted to hire the ML's father, but he escaped and fled the country. The FL vowed to collect the ML to take his place, and did so when he returned to Korea but it took a little while to convince him to accept her offer.
• Romance is a Bonus Book - The ML and FL have known each other for over a decade. The FL is a divorced mother having trouble finding a job. The ML works at a publishing company where the FL is ultimately hired. 
• Into the Ring - The FL eventually hires the ML as her secretary. They knew each other for a long time before that.
• K-POP - The Ultimate Audition - The ML and FL have a few unfortunate encounters before the FL is chosen as the newest member of the ML's boy band / k-pop group.
• She Was Pretty - The ML becomes the director of the office where the FL works. Although he doesn't recognize her, they knew each other as children.
• What's Wrong with Secretary Kim - As the title suggests, the FL is the ML's secretary. They met before he hired her.
• Hello Monster - The ML becomes the head of a special investigative team, and the FL is a member of that team. They sort of knew each other before the team was formed.