He is the main lead according to tonight's article from Soompi.https://www.soompi.com/article/1402430wpp/sf9s-rowoon-and-won-jin-ah-confirmed-to-lead-new-office-romance-drama
The synopsis reminds me a bit of "The Village Achiara's Secret" (2015) which was a very good drama. Okay, now I'm missing Yook Sung-jae ~ glad we have "Mystic Pop Up Bar" to watch since he's in the military. https://www.viki.com/tv/28762c-the-village-achiaras-secret
Shin Sun-rok updated his Instagram on May 20th showing the script for "Kairos" and the next day a picture of himself saying 'On the way to work ~~ Kairos'. Yay! Looking forward to this drama.
Chun Suk-tae [1980s], played by actor Jo Doek-hee, prosecuted of Gong Ji-chul at his trial. Chun Suk-tae [present day], played by actor Choi Kwang-il, is Chun Jong-bum's father (not biological but adoptive).
I've only just started episode 15 and I believe the woman sending text messages ['you will kill the person you love'] to Chun Jong-bum is Jang Hye-mi, Baek Sang-ah's mother -- (Baek Sang-ah is engaged to Kim Soo-hyuk). Jang Hye-mi (if I remember correctly) is an author. She is also the individual that 'sponsored' and set up Chun Jong-um in the rooftop apartment; a room she had cluttered with distasteful 'art' which Chun Jong-um took down immediately afterward. Is Jang Hye-mi trying to provoke Chun Jong-um to murder so she can use his actions in her writing? Also, Jang Hye-mi (actress Wie Ji-yeon) is in both timelines (present day and 1980's) but I don't recall her character (although she looks like the lawyer that represented Gong Ji-cheol at his trial) . Is that why she knows who Gong Ji-cheol is.
K-Drama 
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https://www.soompi.com/article/1402913wpp/yoon-hyun-min-and-seo-ji-hoon-show-contrasting-charms-in-1st-glimpse-of-new-rom-com-characters
https://www.soompi.com/article/1402437wpp/kim-soo-hyun-is-hardworking-and-resolute-in-1st-stills-for-upcoming-drama
https://www.soompi.com/article/1402430wpp/sf9s-rowoon-and-won-jin-ah-confirmed-to-lead-new-office-romance-drama
The synopsis reminds me a bit of "The Village Achiara's Secret" (2015) which was a very good drama. Okay, now I'm missing Yook Sung-jae ~ glad we have "Mystic Pop Up Bar" to watch since he's in the military.
https://www.viki.com/tv/28762c-the-village-achiaras-secret
Dramabeans recap on the first episode:
http://www.dramabeans.com/2020/05/mystic-pop-up-bar-episode-1/
Dramabeans recap on the first episode:
http://www.dramabeans.com/2020/05/mystic-pop-up-bar-episode-1/
Chun Suk-tae [present day], played by actor Choi Kwang-il, is Chun Jong-bum's father (not biological but adoptive).
Jang Hye-mi (if I remember correctly) is an author. She is also the individual that 'sponsored' and set up Chun Jong-um in the rooftop apartment; a room she had cluttered with distasteful 'art' which Chun Jong-um took down immediately afterward.
Is Jang Hye-mi trying to provoke Chun Jong-um to murder so she can use his actions in her writing?
Also, Jang Hye-mi (actress Wie Ji-yeon) is in both timelines (present day and 1980's) but I don't recall her character (although she looks like the lawyer that represented Gong Ji-cheol at his trial) . Is that why she knows who Gong Ji-cheol is.
Character list from AsianWiki: http://asianwiki.com/Born_Again
I welcome opinions, corrections, or simply elaborate.
Be sure click the spoiler box.
https://www.viki.com/tv/36408c-unrequited-love
Yes, the drama airs one episode a week on Sunday.