Momo Ayase, a young and hot-tempered girl looking for love, believes that spirits and ghosts are real, while Ken Takakura, a nerdy boy who happens to share a name with Ayase's Celeb Crush, has firm belief that UFOs and aliens exist.

When the two meet by chance, their differing beliefs clash as the two headstrong teens bet to see which of them is more correct. One abduction and possession later, the two find common ground in their shared experiences with the paranormal, though that's only the beginning of their budding relationship. Ghosts, monsters, aliens, romance, missing genitals, and much much more out of this world phenomena stand in the way of them and their future; their universe will never be the same!

https://tvtropes.org/pmwiki/pmwiki.php/Manga/Dandadan#:~:text=Word%20Pur%C3%A9e%20Title%3A%20%22Dan%20(,%22dan%22%20thrown%20in%20front.