Kamen Rider Den-O + Shin-O (仮面ライダー電王＋しん王, Kamen Raidā Den'ō Ando Shin'ō) is the title of a special episode of Crayon Shin-chan initially played as part of a full hour special titled "Crayon Shin-chan Midsummer Night: Here I Come!
It featured a crossover between Shin-chan and the tokusatsu series Kamen Rider Den-O, as well as three regular summer-themed episodes.
As Misae pleads to him to hold it in until he gets to school, Shin-chan manages to get inside, but instead of the toilet he finds himself on the DenLiner and on Ryotaro's face.
Back on the DenLiner, Hana realizes that it must be due to an Imagin, which Shin-chan mispronounces as "Himajin" (ヒマジン, "Bored Person"), including calling Momotaros a red Buriburizaemon, who Momotaros identifies (and summons) as the legendary Imagin.
Den-O destroys the Fatmass Imagin, saving Shin-chan and Misae who leave just in time to find that the bus has left without them.