On May 9, 2025, Netflix Korea announced the release date of its highly anticipated upcoming series, Mercy for None, starring So Ji-sub. The announcement included a poster and a trailer for the drama series. Mercy for None will premiere on June 6, 2025.So Ji-sub will be making a comeback to noir action with this drama after 13 years. Mercy to None revolves around Ki-jun, who has cut his own Achilles tendon and returns to the underworld after 11 years. He seeks revenge for the death of his younger brother Ki-seok and is now determined to uncover the mastermind behind the death.The drama series is based on a popular Naver webtoon of the same name, which depicts the world of cold and intense violence.Mercy for None: Plot and castSo Ji-sub plays the titular role of Nam Ki-jun, who was once a key member of the Bongsan Gang led by Koo Bong-san. He fought through bloody turf wars that helped the gang rise to power.But everything changes when his younger brother, Nam Ki-seok, joins the rival gang Joowoon, which is under Lee Ju-un. To protect his brother, Ki-jun makes a difficult and drastic choice. He leaves the gang and, to prove that he will never return, he cuts his Achilles tendon.Eleven years later, he lives a quiet life, runs a small beverage supply business, and serves establishments owned by Bongsan. He now has no intention of returning to his old ways. However, when Nam Ki-seok, who is now second in command of Joowoon, is found dead under mysterious circumstances, Nam Ki-jun knows he can't stay away.To seek revenge and uncover the truth about his brother's death, he returns to the world he left behind. He comes back to a place where old grudges still linger, power has shifted, and nothing appears as it seems.The cast of Mercy for None includes So Ji-sub as Nam Ki-jun. Ahn Kil-kang portrays Koo Bon-sang's character. Lee Jun-hyuk will make a special appearance as Nam Ki-seok, Ki-jun's younger brother.So Ji-sub debuted as a model but later became known for his roles in television series and movies such as Something Happened in Bali, Rough Cut, Phantom, Master's Sun, and Cain and Abel.Mercy for None: Trailer and promotional posterThe promotional poster for Mercy for None shows So Ji-sub as Ki-jun, who is standing alone in a narrow alley surrounded by fallen men. There is blood scattered on the world, which hints at a fierce battle Ki-jun has faced alone. The poster ignites curiosity about the cold journey of revenge to uncover the secrets behind his brother's death.The official trailer starts with Ki-jun's words (So Ji-sub). He says:"Do you remember the promise we made 11 years old? I kept my word but the two of you didn't keep yours."He is armed with a baseball bat and is seen fighting in an alleyway against several men, showcasing intense action scenes. The trailer ends with a close-up of Ki-jun covered in blood and states:"I need to end this."The trailer raises curiosity about what awaits him at the end of his long and lonely journey.Mercy for None will air on Netflix on June 6, 2025.