Dandadan (ダンダダン), also written as Dan Da Dan, is a Japanese web manga series written and illustrated by Yukinobu Tatsu. It has been serialized in Shueisha's Shōnen Jump+ app and website since April 2021, with its chapters collected in 24 tankōbon volumes as of June 2026. The series follows two teenagers with supernatural powers fighting yōkai and aliens with help from multiple allies.

An anime television series adaptation, produced by Science Saru, aired from October to December 2024. A second season aired from July to September 2025. A third season is set to premiere in 2027.

Momo Ayase is a high school girl who believes in ghosts but not aliens, while her fellow high schooler, Ken Takakura, whom Momo nicknames "Okarun", believes in aliens but not ghosts. In a bet to determine who is correct, the two decide to separately visit locations associated with both the extraterrestrial and the occult—Momo visiting the former, and Okarun the latter. Momo is abducted by a group of aliens who accidentally unblock her chakras, enabling latent psychic abilities. Meanwhile, Okarun becomes possessed by a spirit, and together with Momo's abilities, they use his possessed form to defeat the aliens.

The rest of the story follows Momo and Okarun as they ally with fellow students, friends, family, and new acquaintances to combat supernatural entities, including spirits and extraterrestrial beings, while also navigating the evolving romantic tension between Momo and Okarun. Initially, a central plot focuses on Okarun's quest to retrieve his missing testicles (kintama). After succeeding, the story then shifts to Momo when she becomes afflicted by a mysterious curse that gradually diminishes her physical size and erases her presence to those around her. This development drives the latter half of the plot, as the other characters work to undo the curse and restore Momo to her original state. Although Momo's curse is eventually lifted, she loses most of her memories in the process — including those of her time with Okarun and the others.