Mouse – K-Drama Ending Explained

The Story

Mouse is a story about psychopaths, and specifically about a series of different murders strung together across a long timeline. There’s a lot going on in this show and the chapters are intentionally obfuscated and convoluted to throw viewers off thee scent of what’s really going on.

However, the gist of the plot comes down to two predominant serial killers; the Head Hunter and the Seven Deadly Sins killer. Both of these are integral to the main plot line and both involve Moo-Chi heavily.

There’s a lot going on here and this ending explained is designed to be an accompanying piece to our episode 20 recap and review. You can click HERE to check that out. Otherwise, buckle in and let’s dissect this crime drama.


Who is the Head Hunter? Is he Ba-Reum’s Father?

It’s revealed late on that Ba-Reum’s father is actually the Head Hunter, Seo-Joon. Seo-Joon is the original killer who’s responsible for slaughtering Moo-Chi’s family along with several other deaths too. This backs up the theory throughout the series that being a psychopath is genetic and passed down through the genes.


Who is the Seven Deadly Sins killer? Is Ba-Reum the killer?

Yes, Ba-Reum is the Seven Deadly Sins killer, although he was originally Jae-Hoon (more on that in a minute.) He killed Moo-Won, Bong-Yi’s grandmother, and all the other victims that make up the seven deadly sins. His first killing was Soo-Ho, which is what started this whole mess after several unpleasant instances involving animals. He’s a psychopath through and through, and even pretended to feel emotion after these killings while investigating. He practiced how to show emotion in the mirror and his retching was completely orchestrated too.

Just to make this even more sadistic, Ba-Reum gave Bong-Yi a necklace made of cat teeth from the cats he murdered. It’s not until the surgery that things began to change for him.


Is Yo-Han or Ba-Reum in control?

Ba-Reum and Yo-Han had a fight up on the rooftop. Moo-Chi arrived and shot Yo-Han, believing him to be the serial murderer. Ba-Reum also suffered from some nasty head trauma too.

The Head Hunter was freed from prison to do surgery on Ba-Reum, implanting parts of Yo-Han’s brain into Ba-Reum’s. After, Ba-Reum began to feel empathy but this was simply a side effect to Yo-Han’s brain being implanted. He essentially became an empathetic psychopath and this explains his hallucinations. He soon became self-aware to what’s happening and changed his ways.

However, it’s also revealed that Daniel Lee and Hong-Ju were working together and coerced Ba-Reum into working with them, taking out Duk-Soo by turning this killer against another killer. Ba-Reum however, did this out of love for Bong-Yi.


Who killed Jae-Hoon’s family?

Soo-Ho was the killer, he killed Jae-Hoon’s mother because she was trying to kill her child, which happens to be Ba-Reum. Jae-Hoon’s father died accidentally while he and Soo-Ho wrestled with a knife. When Soo-Ho burned the house, he had no idea that Jae-Hoon’s brother was still inside. Jae-Hee managed to get away and she is now in care, under the alias of Michaela.


Were Yo-Han and Ba-Reum switched as children?

Yes. We find out from Ji-Eun that the two children were switched at birth. It’s not explicitly mentioned but it’s assumed that the reason for this is linked to the psychopath gene. It would perhaps have been easier to kill a child that turned into a psychopath if it wasn’t your own flesh and blood. That’s the theory anyway but the show doesn’t fully explore this idea.


What is the Oz organization? What are their goals?

It’s revealed late on that the Oz organization are the string-pullers for much of the drama going on in the show. They’re fronted by the government official, Choi Young-Shin. She’s a scientist and after the failed abortion bill set to work on a longer plan of action. This involved setting up Yo-Han and Ba-Reum (then under his birth name of Jae-Hoon) as test subjects. This links back to the name of the show of course, likening these two to mice.

Ba-Reum’s “aunt” wasn’t actually part of his bloodline and she came in and adopted the child, working for Oz the entire time. After Soo-Ho killed Jae-Hoon’s family, this was an act of desperation to keep Oz in control of this. She feared for her son’s life because she knew Ba-Reum was a killer and thought he would kill again.

Both men (Yo-Han and Ba-Reum) were watched by government officials with extensive reports sent back to Choi. This while time her ultimate goal was to create a utopian world free of psychopaths. The “Land Of Oz” is what she wanted to call it.


Does Moo-Chi forgive Ba-Reum at the end?

At the end of the drama Moo-Chi visits a grave for Ba-Reum. This seems to be located in a walled-off area where other death-row inmates are buried. Throughout the show we’ve seen the pair grow closer together. After Ba-Reum’s surgery, the pair worked together to find and piece together the various different serial murders, including the Apple killer and the knot-tying killer.

During the finale, Moo-Chi bitterly confronts Ba-Reum in prison. He notices the emotion deep inside him and seemingly became aware that Ba-Reum is regretful of his actions. No matter how sadistic, Ba-Reum’s personal way of asking for forgiveness was to kill his own Father in the exact way Moo-Chi wanted it done.

Although Ba-Reum eventually died in prison, Moo-Chi’s feelings must be conflicted. After all, Ba-Reum killed his own flesh and blood and messed with him for a long time.

It speaks of Moo-Chi’s admirable character that he even shows up at Ba-Reum’s gravestone to mark it off. This seems to indicate that he has forgiven him – at least in a small part. Not necessarily for Ba-Reum’s family slaughtering Moo-Chi’s, but more for Moo-Chi’s own sense of closure.

It’s open to interpretation but we’re going with the theory that he has been forgiven.


Was Ba Reum actually in the church? What was with that scene?

There’s no way Ba-Reum was in the church at the end in anything other than a dream or vision. His sentence was passed to stay behind bars forever. He was on death row and presumably after the Head Hunter murder, moved into isolation.

Throughout the series we’ve seen Jae-Hoon wrestle with what he is, asking the Lord for forgiveness and spitting in the deity’s face by presenting him these Seven Deadly Sin killings. Eventually Ba-Reum is granted his wish in the form of Yo-Han’s emotions.

Ba-Reum was very ill at the end and we learn from Moo-Chi that he lived his final days in pain and misery. Based on this assumption, it could well be that Ba-Reum dreamed up this segment before he passed away. He saw his old self, the Jae-Hoon from childhood, sitting at the front row of the church. They’re alone because, well, that’s how they’ve been their whole life.

Ba-Reum mentions how he’s “not a monster anymore” and his hand eventually drops. The young Jae-Hoon sheds a genuine tear too. This could well be the point where Ba-Reum/Jae-Hoon passes away, with both “sides” of Ba-Reum now gone and his final breath taken.


Is there a post-credit sequence? Who is lying on the operating table?

Yes there is a post-credit sequence to Mouse. Here, we cut back and see the Head Hunter’s video clip being played for a surgeon, who’s currently operating on an unnamed man. This is Kim Yo-Han, a guest star and K-Pop star who’s not part of the overall story.

This seems too hint that the legacy of the Head Hunter is continuing, with the government intent on keeping the Oz operation going. Could it be that two new lab rats are being used in an upcoming experiment?

Don’t bank on a second season though; it’s highly unlikely that this Korean drama will be renewed. However, it’s undoubtedly been a wild ride over the weeks!


Thanks for reading our Ending Explained article! What did you think of Mouse’s ending? Did you guess that Ba-Reum was the killer? Did the show confuse you too with all its twists and turns? Let us know in the comments below!


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2 thoughts on “Mouse – K-Drama Ending Explained”

  1. Thank you so much for the reviews, it was super brilliant and amazing. I was too scared to watch the movie till the end so I read it up here. I’m so pained that Lee Sun Hi later turned out to be the killer, he’s one of my favourite Kdrama actors. Lol. It’s very sad Yo Han died though, he delivered his role 100%, they all did actually. Kdrama never fails to keep you at the edge of your seat. Lol.

    Cheers to more amazing Kdramas 🥂.

    Thanks again The Review Geek, you’re truly a Geek 100%.

  2. This show has me glued to the screen until……….Ba-Reum killed the bird and threw it out of the hospital room window. That was it for me. Despite buying the series on DVD I will not finish watching it! EVER!

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