Ep 1. Episode 1

One Spring Night is a K-drama series about the struggles of modern love. The first episode titled "Episode 1" introduces Jung In, a librarian who is in a long-term relationship with her boyfriend Kwon Ki-seok, who is a pharmacist. However, things start to change when Jung In meets Yoo Ji-ho, a single father and a pharmacist who runs his own store.

The episode begins with Jung In and Ki-seok attending a colleague's wedding. Jung In is feeling uncomfortable since the couple has been together for less time than she and Ki-seok have, but they are getting married before them. This conversation opens up the topic of marriage between Jung In and Ki-seok, who thinks they should wait a little longer before getting married. Jung In is understanding but can't shake the feeling that she wants to take their relationship to the next level.

Following the wedding, Jung In takes Ki-seok's advice and goes to the newly opened pharmacy to get medication for her sick father. There she meets Ji-ho, who helps her get the medicine she needs and even offers to give her a lift home since it starts to pour rain. During their ride, Jung In and Ji-ho exchange pleasantries, and Jung In finds it easy to talk to him.

Jung In's boyfriend Ki-seok is waiting for her when she gets home, and the couple discusses their day while watching TV. Jung In mentions her encounter with Ji-ho, and Ki-seok is not too keen on the idea of his girlfriend receiving a lift from another man, let alone a single father. This exchange sets the tone for some of the conflicts that will arise throughout the series between Jung In's desire to be independent and Ki-seok's possessiveness.

The following day, Jung In goes to the library where she works, and we meet some of her colleagues, including Kwon Hyuk-joon, who seems to have a crush on her. Jung In receives a call from Ji-ho, who is letting her know that the medication her father needs will be available at his pharmacy later that day.

Ji-ho and Jung In have another chance encounter when she goes to pick up the medication, and the two continue to talk and get to know each other more. Jung In discovers that Ji-ho is a novelist and that he became a single father after his wife passed away.

As Ji-ho is getting ready to leave, he finally musters up the courage to ask for Jung In's number, but she hesitates, thinking about her relationship with Ki-seok. Still, she gives Ji-ho her number and tells him that they can be friends.

Towards the end of the episode, we see Jung In reflecting on her relationship with Ki-seok and what she wants from it. She confides in her friends, who give her advice, but in the end, she decides to have an honest conversation with Ki-seok.

Overall, episode one of One Spring Night establishes the main characters and sets up the primary conflict of the show-the struggle between what Jung In wants and what her boyfriend, Ki-seok, thinks is best for their relationship. It also introduces the possibility of a new love interest in Ji-ho and teases at the potential for a love triangle. The show is off to a promising start, and viewers are sure to be invested in Jung In's journey of self-discovery and love.