A former special forces soldier delivers revenge for victims of injustice while working for a secret organization that fronts as a taxi company.

When Kang Bok-Soo was a high school student, he was falsely accused of committing violence and kicked out of school. This was caused by his first love Son Soo-Jung and a male student Oh Se-Ho. Kang Bok-Soo is a now an adult, but his life has not gone smoothly. To get revenge on Son Soo-Jung and Oh Se-Ho, he returns to the same high school as a student. The environment at the school has changed and Kang Bok-Soo gets involved in unexpected cases.

Woo-jin is Korea's top star - every item he wears and uses are always a hot potato and gets sold out overnight. He is especially famous for remembering all his fan names. He seems to be just perfect, but there is one big secret that nobody knows - he cannot forget but only remember things. Woo-jin is forced to relive painful moments over and over again, feeling the same amount of anguish each time. One day, Woo-jin encounters a woman named Hae-soo, who suffers from the opposite pain from him: her memory resets every 30 days.