Character Relationship Map: I Saw the Devil

Characters

• Kyung-chul (played by Choi Min-sik) — protagonist

  Serial killer and school bus driver who murders the victim and scatters her remains. Evades police, survives multiple assaults by the agent, plants a tracker on a taxi driver, kills the victim's fathe...

• Squad Chief Jang (played by Jeon Kuk-hwan) — supporting

  Victim's father who leads the police search alongside Squad Chief Oh. Provides suspect information to the agent and is later brutally assaulted and killed by the serial killer while trying to protect...

• Section Chief Oh (played by Cheon Ho-jin) — supporting

  Police squad chief who co-leads the initial investigation and search for the dismembered victim alongside Squad Chief Jang.

• Se-jung (played by Kim In-seo) — supporting
• Kyung-chul's Son (played by Jang Jeong-won) — minor
• Section Chief's Daughter (played by Nam Bo-ra) — supporting

  Refers to Squad Chief Jang's daughter, identified in the plot as Jang Se-yun. She is targeted and killed by the serial killer to disrupt the agent's pursuit.

• NIS Agent (played by Lee Jun-hyuk) — supporting

  Refers to the agent's trusted subordinate. He assists both the agent and the serial killer with hospital treatment and helps them evade police custody, enabling the continuation of their private tortu...

• Tae-joo (played by Choi Moo-seong) — supporting

  Friend of the serial killer and a cannibalistic murderer. He hosts the killer, gets caught in the crossfire, is arrested by police, and reveals crucial information about the killer's next targets befo...

• Section Chief Oh's Wife (played by Nam Hyeon-joo) — cameo
• Kyung-chul's Mother (played by Son Young-soon) — cameo

Canonical Relationships

Family, romantic, and professional connections based on plot evidence.

• Section Chief Oh's Wife → Section Chief Oh (wife)
• Kyung-chul's Mother → Kyung-chul (mother)
• Kyung-chul's Son → Kyung-chul (son)
• Section Chief's Daughter → Section Chief Oh (daughter)
• Squad Chief Jang → NIS Agent (Professional Investigation Contact) — The police chief supplies investigative information that enables the agent's pursuit.

  Squad Chief Jang provides the agent with information about the suspects connected to the victim's murder.

• Tae-joo → Se-jung (Romantic Girlfriend) — They are an intimate couple connected through Tae-joo's household.

  The plot identifies Se-jung as Tae-joo's girlfriend when Kyung-chul visits Tae-joo's home.

Story Dynamics

Alliances, conflicts, and narrative interactions that evolve throughout the story.

• Se-jung → NIS Agent (Conflict Hostile Encounter) — Se-jung is caught inside the agent's assault on Tae-joo's household.

  The agent arrives at Tae-joo's home and incapacitates Tae-joo and Se-jung during the confrontation.

• Tae-joo → NIS Agent (Narrative Information Source) — Tae-joo becomes an unwilling source of information for the agent.

  The agent questions Tae-joo in the hospital and learns that Kyung-chul is targeting Squad Chief Jang and another family member.

• NIS Agent → Kyung-chul (Conflict Tormentor) — The agent deliberately prolongs Kyung-chul's suffering instead of killing him immediately.

  The agent tracks Kyung-chul with a swallowed transmitter, fractures his arm, attacks him repeatedly, and cuts his Achilles tendon.

• Kyung-chul → Se-jung (Social Acquaintance) — Se-jung knows Kyung-chul through her relationship with Tae-joo.

  Kyung-chul meets Se-jung at Tae-joo's home, where she appears nonchalant about his arrival.

• Kyung-chul → Squad Chief Jang (Conflict Enemy) — The serial killer becomes the police chief's direct enemy after targeting his family.

  Squad Chief Jang leads the police search after the remains are discovered. Kyung-chul later brutally assaults and kills him at his home.

• Kyung-chul → Tae-joo (Social Friend) — Tae-joo is Kyung-chul's criminal associate and personal acquaintance.

  Kyung-chul visits Tae-joo's home after being attacked, and Tae-joo comments on the identity and motives of the person tormenting him.

Story Analysis

A killer and his pursuer become trapped in an escalating cycle of cruelty that turns revenge into another form of devastation.

Plot Progression

1. Murder And Investigation — Kyung-chul murders a stranded woman and disposes of her remains. The discovery prompts Squad Chief Jang to organize a police search and share suspect information with the agent.
2. The Tracker Of Vengeance — The agent identifies Kyung-chul through the recovered ring and begins a campaign of repeated attacks. Instead of ending the pursuit quickly, the agent implants a transmitter and keeps the killer alive...
3. Violence Without Escape — Kyung-chul continues attacking people while trying to recover from the agent's assaults. His refuge with Tae-joo and Se-jung becomes another battleground when the agent tracks him there.
4. The Killer Strikes Back — Kyung-chul removes the transmitter and redirects it to a taxi driver. Information from Tae-joo reveals that the killer is targeting Squad Chief Jang's family, but the warning comes too late.
5. The Cost Of Revenge — The agent abducts Kyung-chul and constructs a booby-trapped guillotine at the killer's house. Kyung-chul dies as his family arrives, leaving the agent devastated by the consequences of revenge.