Welcome to Demon School! Iruma-kun

Attorney Oh Su Jae will do whatever it takes to win the trial. On the day she beats all of her male competitors and becomes the representative lawyer of TK Law Firm, she becomes embroiled in an irreparable incident.

Oh Su Jae, who was demoted to an adjunct professor at the law school after the Park So Young incident, decides to take on the role of director of the school's Legal Clinic Center in order to create a favorable public opinion toward him.

Park Ji Young appears at law school and says Professor Oh Su Jae killed her older sister Park So Young. Oh Su Jae decides to take on Park So Young's case as Legal Clinic's first case, and the Legal Clinic members begin their own investigations.

The information that Legal Clinic Center members reported to Oh Su Jae was used as an excuse to have Park Ji Young arrested by the police. They obtained important information that can release her and prove that Park So Young's case was a murder.

Oh Su Jae refused police investigation even after being robbed in a mask. The reason Su Jae was attacked was because Choi Tae Gook, Han Seong Beom, and Lee In Su were all holding USBs that actually belongs to Gong Chan..!

Oh Su Jae and the members of Legal Clinic decide to find the 'real culprit' of Park So Young's case, which is clearly a 'murder', while also completing the sale of Hansu Bio.

Hong Seok Pal was identified as a suspect in the Park So Young case. He dies leaving only a recording of his phone call with Oh Su Jae. Meanwhile, Choi Tae Gook seems to have planned this situation, taking advantage of the moment when Oh Su Jae is away.

While Oh Su Jae is in prison, Choi Tae Gook takes everything that Oh Su Jae had been holding onto. The members of Legal Clinic are working hard to clear Oh Su Jae of the charges and Choi Yoon Sang starts taking dangerous action with Gong Chan.

Oh Su Jae decides to stay at Gong Chan's house and spends happy days forgetting the heavy reality for a while. Meanwhile, Choi Yoon Sang leaves the Legal Clinic Center and begins her internship under Oh Su Jae by entering TK Law Firm.

Oh Su Jae and Gong Chan confirmed their feelings for each other at the beach. Ji Soon Ok, who came to the Legal Clinic Center, hears Gong Chan's voice and cries out as Kim Dong Gu, and learns Gong Chan's identity one by one...

Gong Chan goes to the police station, claiming that the skeleton from Yeongpyeong district is his younger sister, Jeon Na Jeong. Oh Su Jae, who realizes that Gong Chan is Kim Dong Gu, is confused and pushes Gong Chan away.

Gong Chan still has doubts about Noh Byeong Chul, the real culprit of the murder case in Woongju. Oh Su Jae digs into the case based on what Gong Chan has investigated so far, while Gong Chan learns about Su Jae's hidden actions during the past trial.

Meanwhile, Seojung University Law School holds a mock court, and Choi Tae Gook appears and confronts Gong Chan. The members of Legal Clinic and Oh Su Jae join forces to confront the incident from 10 years ago, and Choi Tae Gook pours out words Su Jae.

The members of Legal Clinic learn that Choi Joo Wan, Han Dong Oh, and Lee Si Hyuk are involved in an incident 10 years ago. Oh Su Jae points out Choi Tae Gook's weaknesses and presents a contract to him... but Oh Su Jae's daughter disappears.

Oh Su Jae disappears after attending the funeral of her daughter. Gong Chan is endlessly looking for her. The puzzles of a case from 10 years ago begin to come together and Choi Tae Gook opens a lawyer disciplinary committee to throw out Su Jae.

Oh Su Jae failed to properly explain the suspicions raised against her. Against the evil deeds of Choi Tae Gook and all evildoers, including the incident 10 years ago and until now, the members and Oh Su Jae begin their final argument.