13 timestamped notes explaining the Korean cultural context in this episode — customs, idioms, food, honorifics, and history, at the moment each appears on screen. These notes discuss events across the whole episode. To see them revealed scene-by-scene as you watch, use the episode page to find an airing.
The show opens with a predator's internal monologue using 사냥 (sahyang, 'hunt') and 사냥감 (sahyang-gam, 'prey'). This hunting metaphor is a deliberate echo of the drama's core idea — that a born predator sees human life the way a hunter sees an animal. The word 숨골 (sum-gol) he uses for 'windpipe' is an older, visceral term rarely heard in everyday speech, underlining just how coldly clinical his mindset is.
실험 쥐 (sirhŏm jwi) literally means 'lab rat' or 'experimental mouse' — the same word as the drama's title, 마우스 (Mouse). The characters are horrified to realise the word ties their whole ordeal back to being unwitting subjects in someone else's experiment. Korean drama titles often carry a layered meaning that clicks into place at a key scene like this one.
The speaker uses the English loanword 트리거 (trigger) — borrowed directly into Korean — to explain how someone deliberately fed him targets to reawaken his killing urge. The idea that a third party engineered each murder by pulling his psychological 'trigger' reframes every crime in the series as a controlled experiment rather than spontaneous violence.
국민 아들 (gungmin adeul) means 'the nation's son' — an affectionate Korean internet title given to a young public figure that the whole country has collectively adopted as a beloved younger brother or son. In Korea, viral sympathy can make someone untouchable overnight, which is why beating up Jung Ba-reum on camera is treated as a career-ending catastrophe for the detective.
직위 해제 (jig-wi hae-je) is an official administrative suspension — the officer keeps his rank and pay but is barred from performing any police duties. In Korea it can be ordered directly by the 청장 (commissioner) without going through a full disciplinary hearing, which is why it happens so fast here. It's a real procedural step distinct from being fired or criminally charged.
성모 사랑의 집 means 'House of the Blessed Mother's Love' — the 성모 (Sŏngmo) is the Virgin Mary in Korean Catholicism. Small residential care homes run by Catholic orders or parishes are common across Korea, often caring for children with disabilities or developmental conditions. The name signals the institution is faith-run and quietly important to the show's thread connecting Song Su-ho to the church.
The nun describes the visitor's eyes as full of 고통 (gotong, suffering) and 회한 (hoehan, deep remorse or regret). 회한 is a heavier, more literary word than ordinary regret — it carries the sense of grief over something that cannot be undone. It's closely related to 한 (han), the uniquely Korean concept of sorrow and resentment accumulated over a lifetime, often discussed in Korean culture and literature.
The line about being mocked for being a 헤드헌터 (headhunter) son is a small but real social detail. In Korean society, certain occupations — including private recruiters, debt collectors, and repo agents — have historically carried a low-status or ethically murky image, and children could genuinely be teased at school because of a parent's job. The stigma is fading but was especially sharp in older school environments.
The secret group is called OZ — the same initials causing confusion earlier when a tattoo was misread as 'OZ' instead of 'OJ'. Using a Western-looking acronym for a shadowy Korean organisation is a common thriller device in K-dramas; it signals the group operates beyond ordinary institutions. The audio message treats even naming OZ out loud as dangerous, raising the stakes around who has been listening all along.
Sung Yo-han describes being 손가락질당해 — literally 'pointed at by fingers', meaning publicly shamed or gossiped about — because his father was a 헤드헌터 (headhunter, here implying a hired killer). In tightly knit Korean school and neighbourhood communities, a child's identity is strongly tied to family reputation, and social exclusion based on a parent's perceived wrongdoing is a recurring theme in Korean dramas and real life alike.
The scene turns on the realisation that a key piece of physical evidence — a knife wound on the attacker's arm — was never formally entered into the case record. In the Korean police system, a 진술서 (jinsulseo, written witness statement) is a formal document and its contents are treated as the official record. If something isn't in the 진술서, investigators act as if it was never said, which is exactly the loophole being exposed here.
A 매직박스 (magic box) is a standard stage-magic prop — a cabinet fitted with angled mirrors so that a person hidden inside seems to vanish or transforms into someone else. The angled mirror the crew member mentions is the key mechanism: a mirror set at 45° reflects the side walls so the box appears empty. The detail matters here because it explains how a body could have been moved in plain sight during a busy performance.
재무 3팀 (Jaemu Sam-tim) means 'Finance Team 3' — a deliberately bland corporate name designed to hide in a company org-chart. Kim Jun-seong hacking into it and then going silent suggests it was a front account or data silo for OZ's operations. Using a fake internal department as a money or information conduit is a real corporate crime tactic, and its mundane name is meant to make it invisible to a casual audit.