A strange girl with amnesia shows up at Ryunosuke's house and tells him to call her Nuku Nuku; Ryunosuke's mother Akiko is tasked by Mishima to retrieve their missing Androbot.

Ryunosuke's parents go on vacation, leaving him and Nuku Nuku home alone together; it's a dream come true for Ryunosuke, until their neighbor's nosy young daughter, Non, butts in; Mishima sends a prototype Androbot after Nuku Nuku.

Nuku Nuku and Ryunosuke go on a walk through the city and show each other their favorite spots, but the mood sours when Nuku Nuku's a little too trusting of strange men.

Akiko is appointed chief of the Runaway Androbot Capture Project and assigned two subordinates, Kyouko and Arisa, who immediately start causing trouble.

Ryunosuke's friends spot him with Nuku Nuku and he tries to convince them that she is his girlfriend, but he accidentally sets her up on a date with his buddy, Tsubouchi.

A special cat escapes from the Mishima labs, and Akiko is told to find it; Nuku Nuku finds kittens outside and brings them back to the Natsume house; Akiko's underlings go wild again, and it's up to Nuku Nuku to stop them.