Because This Is My First Life

Because This Is My First Life is a 2017 South Korean television series starring Lee Min-ki and Jung So-min that explores different points of view on careers, relationships, marriage, and love. The series marks Lee Min-ki's first small screen lead role since 2007. It aired on tvN from October 9 to November 28, 2017, every Monday and Tuesday at 21:30 (KST).

Synopsis
Socially awkward IT employee Nam Se-hee (Lee Min-ki) and broke homeless writer Yoon Ji-ho (Jung So-min) agree to a marriage of convenience by signing a contract of two years, wherein they agree to the terms and conditions of only being landlord and tenant, sharing their home based on common goals and values. Things do not go as planned when the housemates' pact of platonic cohabitation is interfered with by their personal trauma, social expectations, and familial interventions.

The series also follows the lives of the friends of Se-hee and Ji-ho and their different perspectives on love and marriage.

Main

 * Lee Min-ki as Nam Se-hee, a quirky and apathetic computer designer who has bought an expensive townhouse and rents out his extra room to help with the mortgage. He spends his days at work or home with his cat and has no plans to date or marry. After a series of bad tenants, he rates Ji-ho very highly and, believing she is a male, he offers her the room.
 * Jung So-min as Yoon Ji-ho, an assistant screenwriter who moves out of the home she shares with her brother when he marries his pregnant girlfriend. Currently between projects, she rents the room from Se-hee (who she thinks is female) because the rent is affordable and no deposit is required. After working hard at her career throughout her twenties, at age 30 she has never dated and has a career crisis that causes her to rethink her goals.

Supporting

 * Esom as Woo Su-ji, a school friend of Ji-ho who works in a corporate office. Her dream was to be the CEO of her own business but she is trapped in a well-paying position where she must bear with frequent sexual harassment from her male colleagues.
 * Park Byung-eun as Ma Sang-goo, friends with Se-hee since college and CEO of the company where Se-hee works.
 * Kim Ga-eun as Yang Ho-rang, a school friend of Ji-ho who is a hostess at a restaurant/bar and dreams of becoming a wife and mother.
 * Kim Min-seok as Sim Won-seok, Ho-rang's long-time boyfriend who is the CEO of a startup company which is having problems getting an investor.

People around Nam Se-hee

 * Kim Eung-soo as Nam Hee-bong, Se-hee's father who is a former high school principal.
 * Moon Hee-kyung as Jo Myung-ji, Se-hee's mother who is a full-time housewife.

People around Yoon Ji-ho

 * Kim Byeong-ok as Yoon Jong-soo, Ji-ho's father who is a car center operator.
 * Kim Sun-young as Kim Hyun-ja, Ji-ho's mother who is a full-time housewife.
 * Noh Jong-hyun as Yoon Ji-suk, Ji-ho's younger brother.
 * Jeon Hye-won as Lee Eun-sol, Ji-suk's pregnant wife.

Extended

 * Kim Min-kyu as Yeon Bok-nam, a colleague of Ji-ho's.
 * Lee Chung-ah as Go Jung-min, Se-hee's ex-girlfriend, a successful businesswoman.
 * Yoon Bo-mi as Yoon Bo-mi, a data analyst who works with Se-hee.
 * Hwang Seok-jeong as Writer Hwang.

Special appearances

 * Yoon Doo-joon (Episode 1)
 * Yoon So-hee (Episode 1)
 * Kim Wook as a director

Production
The series is directed by Park Joon-hwa, and written by Yoon Nan-joong. The first script reading session of the cast took place on August 25, 2017 at Studio Dragon in Sangam-dong.