Mr. Plankton

About this title

Mr. Plankton is a 10-episode Netflix romantic comedy about Hae Jo, who runs an errand service and sets out to find the biological father he has never met after receiving a terminal diagnosis, and his ex-girlfriend Jae-mi, who is about to be married and gets swept up in his journey. It was written by Jo Yong of It's Okay to Not Be Okay and directed by Hong Jong-chan of Juvenile Justice.

Netflix released it worldwide on November 8, 2024. The Netflix Korea page lists it as a 2024 limited series rated 15+. The title compares Hae Jo's fate, drifting along without ever settling anywhere, to plankton, the tiny organisms that float with the currents. Netflix announced the casting of Woo Do-hwan, Lee You-mi, Oh Jung-se and Kim Hae-sook in July 2023, when it confirmed the production. Filming took the crew across the country, from Gangwon Province to Jeju Island, over three seasons from summer to winter, with locations including fields and rice paddies in Wanju, North Jeolla Province, Dangnam-ri Island in Gyeonggi Province and snowfields in Pyeongchang, Gangwon Province.

Hong Jong-chan directed the dramas Dear My Friends (2016), Live Up to Your Name (2017) and Life (2018), as well as the Netflix series Juvenile Justice (2022). Jo Yong wrote tvN's It's Okay to Not Be Okay in 2020. Hong described the series as one in which the characters matter above all, saying he worked hard to find the best possible fit for each role and hoped viewers would pay attention to the performances and chemistry of the entire cast, not just Hae Jo, Jae-mi and Eo Heung.

Woo Do-hwan plays Hae Jo; Lee You-mi plays Jo Jae-mi; Oh Jung-se plays Eo Heung, Jae-mi's husband-to-be and the fifth-generation only son of a traditional head family; and Kim Hae-sook plays Beom Ho-ja, Eo Heung's mother, who has been the daughter-in-law of that head family for 60 years. Beom Ho-ja is also the head of a midsize company that runs the family's food business. In episode 1, Hae Jo, who has been passing dull days running his errand service, takes a request from Noh Yang-hui (Lee Da-hee) to kidnap her from her own wedding, and runs into his ex-girlfriend Jae-mi in an unexpected place. On the day Hae Jo learns he has a tumor in his head and is given a terminal diagnosis, he finds out that Jae-mi, who longed for a family and was set to marry into a head family, has been diagnosed with premature menopause. In episode 2, Hae Jo decides to set out in search of his biological father, but first he shows up at Jae-mi's wedding and takes her away with him. Kim Min-seok plays Kkari, Hae Jo's sidekick; Lee El plays Bong-suk, who has been by Hae Jo's side since childhood; and Oh Dae-hwan plays Wang Chil-seong.

At the launch press conference held in Seoul on November 4, 2024, Hong said that plankton are invisible to the naked eye yet produce oxygen, and that the title carries the idea that all of us, like plankton, are sparkling and precious. Responding to concerns raised about the premise in which Hae Jo forcibly takes Jae-mi with him on her wedding day, he said it is up to viewers to decide whether they understand the character's actions, but that the emotional arc clearly shows why he behaves the way he does. Woo Do-hwan said he had badly wanted to do the role from the moment he read the script but had no idea it would be so hard to portray a life facing death, and Kim Hae-sook said she had never known Korea had such beautiful places. In its second week (November 11–17), the series ranked fifth in the global non-English TV category of Netflix's weekly chart with 3.2 million views (hours viewed divided by runtime), and it was reported to have made the Top 10 in 42 countries, including Korea, during the same period.

See alsoIt's Okay to Not Be Okay 2020Juvenile Justice 2022Dear My Friends 2016

Drama Lineup editors · Fact-checked against: wikitree.co.kr, kukinews.com, isplus.com, enews.imbc.com, nocutnews.co.kr, netflix.com, sports.khan.co.kr, about.netflix.com · 2026-10-18