Ash, Misty, and Brock are resting in a forest. Ash starts swinging on some vines, but he slams into a tree. Pikachu runs over to make sure Ash isn't hurt when they both see a small Pikachu watching them. Ash, Pikachu, Misty, and Brock chase after the small Pikachu and the small Pikachu leads them to a large group of wild Pikachus. Pikachu says hello to them, but the group runs off scared. But the small Pikachu stays behind and shakes tails with Pikachu. The group of Pikachu comes back and they play with Pikachu. Brock says the small Pikachu must have accepted Ash's Pikachu into their party.
Ash runs out from behind the rock he, Misty, and Brock have been hiding behind and says he wants to be a part of the group too. When he runs out from behind the rock, Ash accidentally scares away the group of wild Pikachu. Later, Ash asks Brock and Misty why the Pikachu ran away.
Brock says that the Pikachu must have been scared away by Ash because the Pikachu aren't used to seeing humans. The small Pikachu, watching them, falls into a river and Ash's Pikachu jumps into the river to save the small Pikachu.
Suddenly, all the other wild Pikachu all join tails to save Ash's Pikachu and the small Pikachu and they succeed.
Team Rocket watches the group of wild Pikachu and decide they would be a good present for the boss and they make plans to catch them.
That night, all of the Pikachu including Ash's Pikachu sing the Pikachu chant. Ash and his friends see how happy Ash's Pikachu is. Ash was sad but said its nothing. Ash stays up while Misty and Brock sleep. He watches the campfire and sees Pikachu face in it. Ash thinks that maybe Pikachu should be with its own kind. The campfires dies as Ash sees an image of Pikachu running away. Suddenly, all of the Pikachu yell for help. Ash and his friends run over to where the cries were coming from and they find all of the Pikachu trapped in an electric proof net.
James traps Ash and his friends in a net, but they easily get out of it. Team Rocket starts flying away in their balloon taking all of the Pikachu with them. Ash's Pikachu chews a hole in the net and jumps out of the net. Ash and his friends hold out the net they were trapped in to catch Pikachu. They catch Ash's Pikachu and all of the other Pikachu follow Ash's Pikachu out of the net. Ash's Pikachu bit a hole in Team Rocket's balloon and Team Rocket goes blasting off again.
Ash starts walking away without Pikachu. Misty and Brock catch up to him and ask him why he's leaving Pikachu. He says Pikachu would be happier with the wild Pikachu. Pikachu starts following Ash and Ash tells him to stay behind.
Ash runs off, struggling not to give into his emotions with Misty and Brock running after him, calling his name. Pikachu is left behind, shocked and confused.
As he continues to run, Ash finds himself remembering all the things they've been through together including their first meeting, saying goodbye to Ash's Butterfree among other things. The memories end with an image of Ash and Pikachu laughing at when Haunter scared Misty and Brock into leaving the Pokemon Towerr.
In the present, Ash finally stops running. Misty and Brock catch up to him, asking why he's leaving Pikachu. Ash stands his ground, stating that Pikachu will be much happier with its own kind in the forest.
Suddenly, the sun comes up and a familiar shadow is seen. Brock, Misty and then Ash all glance over at the figure and sure enough, it's none other than Pikachu who's obviously overjoyed at seeing the group once again while Ash is stunned by Pikachu's appearance.
As it stands there, the other Pikachu emerge from Pikachu, all together in a single group as Ash, Brock and Misty look on in disbelief.
The little Pikachu that Pikachu itself attempted to save comes up to Pikachu and the two shake tails. The rest of the Pikachu cry out, leaving Pikachu stunned.
The group then begin cheering as loud as they can.
Misty wonders what they're doing. Brock tells her that the other Pikachu are cheering, not only for Ash but also for Pikachu as well. Ash is stunned.
Encouraged by their cries, Pikachu leaves to rejoin Ash, running along the path before eventually jumping into Ash's arms, choosing him over its own kind much to Ash's joy.
As they embrace, Ash, overwhelmed with emotion, begins crying while still hugging Pikachu with the cheers of the wild Pikachu echoing in the background and the sun behind them as well.
- The "Who's that Pokémon?" in this episode is Pikachu.