[4] The series tells the story of three women from very different backgrounds who have met in a hospice and decided to take down one bad person with the limited time they have left.

[25] Park Sung-hoon was initially cast as Min Woo-cheon however he stepped down from the series on July 14, 2021, due to scheduling conflicts and personal reasons.

[26] On October 25, 2021, it was reported that Kang Ye-won was in self-quarantine after contracting COVID-19 after performing a self-test while she was not scheduled for filming as part of the production recommendation.

[29] The series received favorable reviews from critics and viewers as a well-made drama despite its late night time slot.

[30] IZE magazine called The One and Only “the birth of a masterpiece that many people need to see.”[31] Another critic praised the acting stating: “The outstanding performances of the actors are not to be missed.