Mystic Pop-up Bar tells the story of a mysterious pojangmacha (outdoor drinking establishment) run by an ill-tempered woman named Weol-ju (Hwang Jung-eum), an innocent part-time employee named Han Kang-bae (Yook Sung-jae), and a former afterlife detective known as Chief Gwi (Choi Won-young) who visit customers in their dreams to help resolve their problems. Kang-bae has a unique ability that is useful to Weol-ju - with a touch, he can make people pour out all their troubles. This is very useful to Weol-ju who needs to settle the grudges of 100,000 souls.
A hot-tempered woman who is the owner of Mystic Pop-up Bar. 500 years ago, Weol-ju healed the Crown Prince through his dreams but was falsely accused of seducing him, and was targeted by an assassin who killed Weol-ju's mother instead. Weol-ju's sin was committing suicide on the Sacred Tree, causing it to lose its power on a conflict that took 100,000 lives. For the past 500 years, she was sent to the Living Realm to settle the grudges of 100,000 souls and comfort them as a punishment to atone for her past sin.
A cheerful young man who has the ability to make people confess the truth by making physical contact with them. Hence, he creeps the people around him and grew up being an outcast. He worked with Weol-ju as she promised him to get rid of this unique ability in exchange. He is eventually revealed to be the spirit of Weol-ju and Yi-Hon's unborn child which was cursed with the Sorrow of the Sacred Tree.
Formerly the Crown Prince who fell in love with Weol-ju but was unable to protect her, so he slew the instigator of her death, his former best friend, Kim Won-hyung. Once worked for the Afterlife Police Agency, he was given a chance to work as the manager at Mystic Pop-up Bar to be at Weol-ju's side.
In his past life, he was a minister at the palace, mentor of the Crown Prince and father of Won-hyung. His loyalty and dedication for the prince had driven him away from his son. In the present, he became an angel of death who is Chief Gwi's best friend and frequently visit Weol-ju's pop-up bar.
He is Lord Kim Jin's son and Crown Prince Yi-hon's best friend, however his coup d'état was uncovered and he was beheaded by the Crown Prince on his sister's and prince's wedding day. In present day, he escaped from his punishment as an evil spirit to get revenge upon Crown Prince Yi-hon and Weol-ju.
The only human who is immune to Kang-bae's ability. She was Chairman Choi's personal bodyguard but after her encounter with Weol-ju and Kang-bae, she was fired from her job and eventually became security guard of Kapeul Mart. Although Kang-bae and Yeo-rin love each other, her trauma with her past boyfriends causes her to deny her feelings. She is later revealed to be the reincarnation the spirit of the Cinnabar in a nearby cave, a mineral that protects against evil.