The Cave of Mirrors! (Japanese: うつしみの洞窟！鏡の国のサトシとサトシ！？ Reflection Cave! Mirror World Ash and Ash!?) is the 37th episode of Pokémon the Series: XY.
While travelling in the Reflection Cave, Ash's reflection takes Pikachu away from him, prompting him to follow into a world within the reflection, leaving Clemont, Serena, and Bonnie to find a way to bring him back. After Ash arrives in the Mirror Dimension, he discovers that his mirror self needs help finding his Pikachu.
The heroes came to a cave, where Bonnie and Serena are excited to visit. They enter the cave and see many crystals. Bonnie and Serena tell this is the Mirror Cave, where the crystals can reflect appearances. Clemont tells that these aren't ordinary rock crystals. Ash finds a tunnel, so runs through it. On his way, he passes a crystal, and for a moment, a picture of him appears looking the other way. The heroes get lost in this cave, which is actually a maze. Ash tries to go back, with Clemont, Serena and Bonnie following him. Ash goes to a dead end and goes for a bit. He yells to his friends, who tell him to stay where he is. Ash visits a mirror crystal and sees his reflection. Suddenly, the reflection takes Pikachu, so Ash struggles to get Pikachu back and goes inside the crystal. Serena, Clemont and Bonnie arrive, only to see Ash went into the crystal.
Ash goes out of the cave and sees the place slightly stranger. Serena comes and scolds Ash, calling him a crybaby. Bonnie appears and yells to his brother (in a polite way) Ash came. Clemont runs, but he passed Ash and runs back for a bit. Ash is surpised to see how fast Clemont, but Clemont tells he has always been a fastest runner. Serena asks where Pikachu went. Ash reports that his reflection came and took Pikachu, but his friends claim he is speaking nonsense. Ash claims it is true, but Serena suspects that Ash is not himself. Clemont tells that the cave has many mirrors, which lead to alternate worlds. Serena tells Clemont is speaking gibberish, but Clemont knows this is not crybaby Ash they see now in front of him. Ash knows for certain these Serena, Clemont and Bonnie are not the ones he knows. Serena is annoyed by him, so challenges him to a battle to back up those words, which Ash accepts.
Serena sends Fennekin against Ash's Froakie. Fennekin uses Flamethrower, which gets countered by Froakie's Water Pulse. Fennekin goes to scratch, but it attacks an illusion made via Double Team. Froakie uses Bubble, defeating Fennekin. Ash calls Froakie back, so Serena believes Ash, as she wouldn't lose to him. Clemont wonders where is the crybaby Ash. The other Ash appears with original Ash's Pikachu. The other Ash tells when he lost his battle against Serena, she taunted him a lot, so he went away into the cave. The other Ash got lost, as well as his Pikachu. He looked at a crystal and saw original Ash and Pikachu, so took Pikachu away, but soon realized it was not his own. This Mirror Ash apologises to the real one and tells his Pikachu always causes trouble.
The Mirror Pikachu battles the original Team Rocket, using Thunderbolt and Iron Tail. However, Jessie manages to capture it and right after, Meowth questions that is this the same Pikachu they know and love but Jessie exclaimed that they saw it and could be one of him. Ash decides to look for Mirror Ash's Pikachu, but Mirror Bonnie and Mirror Serena wonder how will they search. Meanwhile, the true Serena, Bonnie and Clemont see that Ash is not coming back. Clemont decides to use a new machine to open a portal to different dimension, warping time and space. However, the machine blows up. Meanwhile, Mirror Clemont makes a circle and drops his stick, which reveals where Mirror Pikachu is. While Mirror Bonnie praises Mirror Clemont, her real world counterpart chides Clemont. However, she, Clemont and Serena are worried they may not see Ash again.
Team Rocket sees Mirror Pikachu is persistent, but hide as they hear someone. Ash and the mirror heroes came to a dead end, while Team Rocket sees the Mirror Ash has a twin, as well as a Pikachu. Mirror Ash cries, as he may never see his partner again. Ash tells him they will find Mirror Pikachu, but, suddenly, his Pikachu is captured. Ash sees Team Rocket, Serena was confused because their Team Rocket call themselves the heroes of justice. Mirror Ash sees his Pikachu and Mirror Bonnie calls them the bad Team Rocket, while Jessie and James send their Pokémon. Mirror Ash and Ash send Mirror Hawlucha and Hawlucha, who use Karate Chop. Inkay is hit, while Mirror Hawlucha passes by Pumpakboo, who tackles it. Inkay uses Psybeam, but Ash's Hawlucha comes, protecting the Mirror one. Ash's Hawlucha is confused, so he calls it back.
Pumpkaboo uses Shadow Ball, knocking out Mirror Hawlucha. Mirror Ash calls it back and cries, giving up hope. Ash tells him that it is not over yet, as crying will not do him any good. Mirror Clemont sneaks up and takes both Pikachu. Meowth objects, but Mirror Clemont steps on him and goes away, while Mirror Serena sends Mirror Fennekin, who uses Hidden Power, unlocking the cages. Pikachu and Mirror Pikachu are rescued and use Thunderbolt on Team Rocket, blasting them off. Mirror Ash's friends compliment Mirror Ash for such determination, who thanks Ash for the support. As the sun sets, Clemont remembers according to legend, people who stay in the different world will not come back.
They come back to the crystal, but do not see how to activate it. Mirror Ash remembers that he wished for Pikachu and the portal opened. Mirror Clemont sees feelings open the portal, so Ash wishes to travel with his friends back in his world. Suddenly, the portals open, so Clemont, Serena and Bonnie see Ash and their counterparts. The mirror heroes tell that the sunset is near, so the portals will close soon. The heroes wish that Ash travels with his friends again, which brings the portals close together. The portals begin to separate, so Ash jumps. He trips over, but his friends catch him and pull him back. Ash thanks to his friends and they all bid farewell to their mirror counterparts farewell. The heroes are amazed by this event.
Later, they go to the Pokémon Center. Serena asks Ash if they will be together forever, but Ash tells it is obvious they will. Meanwhile, Team Rocket is exhausted from being blasted by a double Thunderbolt. Suddenly, on a peak, they see their Mirror counterparts, who claim they are heroes of justice.
- "Pokémon Quiz": Wobbuffet (JP)
- "Who's that Pokémon": Wobbuffet (US)
In the English dub, Mirror Serena complains at one point of there being too many Ash Ketchums; however, her mouth could be seen not moving whatsoever while the line was spoken.