A strange girl, Atsuko Higuchi, shows up at Ryunosuke's house and tells him to call her "Nuku Nuku." Her tragic past has left her with amnesia... but more importantly, he's head over heels for her! Meanwhile, 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. But a greater disturbance await when Mishima sends a prototype Androbot after Nuku Nuku!

Nuku Nuku and Ryunosuke go on a walk through the city together and show each other their favorite spots. But the mood sours when Nuku Nuku's a little too trusting of strange men. And then Mishima's genius inventor, Oh-izumi, dispatches his deadly flower girl Androbot to turn her into scrap...

Ryunosuke's school friends spot him together with Nuku Nuku, and he tries to trick them into thinking she's his girlfriend. But instead he accidentally sets Nuku Nuku up on a date with his buddy Tsubouchi. He follows her in secret, but little do they know of Mishima's new scheme to capture her...

A very special cat escapes from the Mishima labs, and Akiko is told to find it! Meanwhile, Nuku Nuku finds kittens outside and brings them back to the Natsume house. She and Ryunosuke work hard to care for them. Then Akiko's underlings go wild again, and it's up to Nuku Nuku to stop them!

Nuku Nuku finds an injured girl in a park and brings her home to the Natsume house. She tells them her name is "Yuko"... then they discover she's an esper! Mishima goons break into the house to retrieve her. She runs away with Ryunosuke, but is escaping really what's best for her?

Late at night, a monstrous insectoid robot escapes from Mishima custody and begins destroying everything in sight! Mishima attempts to subdue it, while Ryunosuke rides a motorcycle with his friend nearby, unaware of the danger. Nuku Nuku arrives in the brink of time to save him!

It's all over TV; the German company Zweig is coming to Japan to face off against Mishima's strongest robot, Sangoku Bross. But Nuku Nuku's uneasy for some reason. Zweig's robot takes the announcer hostage, and Sangoku Bross refuses to risk harming her... luckily, Nuku Nuku is in the audience!

Nuku Nuku's lost memories are slowly returning as the young president of Mishima arrives in Maneki City, planning to take over the company division there. But the ex-president has laid a trap to make sure things don't go smoothly. What will happen when Nuku Nuku gets swept up in the revenge plot?

Nuku Nuku's creator, Dr. Higuchi, was thought dead by everyone—until he suddenly appears in front of her! He wants to take Nuku Nuku away with him to live in peace. Meanwhile, Akiko attempts to stop the young president from investigating Higuchi's secret basement lab, but he has a secret weapon...

As chaos erupts in Maneki City, Dr. Higuchi flees with Nuku Nuku, determined to keep her safe. But at the last moment, she refuses to leave. She heads to Mishima headquarters to put a stop to the young president's rampage and battle Mishima's deadliest creation, the second Androbot!