The theme song for the film is a cover of The Monkees' "Daydream Believer" performed by lead actress Mitsuki Takahata.

[10] Napping Princess takes place in two concurrent settings: a near-future Japan, and Heartland, a fantastical realm.

The situation takes a turn for the worse when Momotarō is unceremoniously arrested three days prior to the 2020 Tokyo Olympics and accused of stealing the car company Shijima Motors' secrets.

A suited figure who looks identical to the Heartland king's evil adviser visits the Morikawa home, and is overheard to be searching for both the tablet and Kokone.

With Morio's help, Kokone evades Watanabe and his men and recovers the stolen tablet and bear doll, driving away in the family's motorcycle.

Appearing now as Ikumi (rather than a young Kokone), she swears to help out Peach one last time, then falls to her death and cracks the tablet's glass.

Now, Shijima Motors has changed course and wants to use the once ignored technology to impress the world during the Olympics with self-driving cars, hence Watanabe's frantic hunt for the tablet.

Kokone, prominently carrying Ikumi's old bear doll Joy, finds Chairman Shijima, who talks of his regrets.

The King orders Watanabe arrested, while Peach enters the remaining robot to do battle with the Colossus, which Kokone empowers with the tablet.

Watanabe manages to emit a "curse" from his cell phone to sabotage the robot, and the kingdom is briefly engulfed in flames.

[16][17] A short animated spin-off film,[18] Ancien and the Magic Tablet: Another Princess was made available on the Japanese version of streaming service Hulu to build anticipation for the movie release.