It is a clear chilly night on the day of Halloween, and many people and Pokémon are in costumes, going out for trick-or-treating.
All except one.
In an old house, a Mimikyu was peeking out through the window, watching them enjoying the holiday. They felt lonely and sad, wanting to join in on the fun, but they were indecisive of what costume to wear. They moved to the mirror to look, only to become startled upon seeing a scary reflection of themselves.
Mimikyu looked around and found a witch's hat, dress, and broomstick, thinking that would be a great costume to wear. Putting it on, they open the door and head outside, spotting three kids along the way. Deciding to get their attention, they get on the broomstick and fly towards them…only for them to zoom past them, though they did catch their attention.
Mimikyu waves at them as they fly by, but they hit a tree, causing them to fall and its costume to fall off, revealing it. This frightened the three kids and they ran away, screaming. Mimikyu peeks out and becomes nervous that they scared them away, so they head back home and decide to put on a different costume. They find some toilet paper and wrap it around themselves, making themselves into a mummy.
Once they were done, they floated out of the house, to find the three kids once again near a house across from its own. Unfortunately, they didn't realize that the paper was caught in the mirror, so they unknowingly dragged it with them. Once Mimikyu got close to them, they got quickly pulled back by the paper that got caught on the mirror, making them bounce on the door and fly in the air before falling on the ground. The kids didn't notice Mimikyu, but they did see pieces of the toilet paper fall on several houses, confusing them.
Back in the house Mimikyu tried various costumes: a vampire, fairy, alien, etc. However, none of them seem to work for the Disguise Pokémon. Eventually it settled on a simple ghost costume, a long white sheet with holes for the eyes. They decided that it would do.
Back outside, the three kids were receiving candy from a house. Mimikyu peeked from the bushes, feeling nervous but also eager to join them. Once they were done, the trio left the house, but the little boy dropped his costume mask. Mimikyu looks at it and picks the mask up right as the boy goes back to get it. The boy looks at the ghost Mimikyu and the latter gives the hat back to him. The boy smiles in thanks until the wind blows off the ghost costume Mimikyu has, revealing the Pokémon.
The boy looked surprised upon seeing Mimikyu and the latter stared back, feeling nervous that they might scare him away. It runs away and hides in a tree, and breaks down sobbing quietly. They just want friends without spooking them. Why does it have to be lonely? Why did it have to look so creepy? Why can't it just be happy?
They felt a hand pat them softly and looked up to see the boy patting his head with a soft smile. He then hugged him, comforting the poor Pokémon. Mimikyu nuzzled him as a result. The boy got up and held out a hand for Mimikyu to take and they reached out a shadowy hand to hold it. They walked out of the tree to see the older boy and girl looking at them.
Mimikyu got nervous, but the younger boy reassured them with a pat on the head and beckoned the older two to join them. The girl came over and tried to pat Mimikyu, to which they allowed and made a sound of happiness. The older boy patted them on the head too, making Mimikyu happy even more. The younger boy gave Mimikyu its own pumpkin bag and they took it. He took their shadowy hand and the four headed off to continue their Halloween night.
