Dandadan. Volume 17: Yukinobu Tatsu

A nerd must fight powerful spirits and aliens all vying for the secret power of his “family jewel,” so who better to fight alongside him than his high school crush and a spirit granny?!
Momo Ayase and Okarun are on opposite sides of the paranormal spectrum regarding what they’ll believe in and what they won’t. Their quest to prove each other wrong leads them down a path of secret crushes and paranormal battles they’ll have to participate in to believe!
Momo has fallen into a cursed diorama that’s laid out like a giant game board. There, she meets a guy named Zuma—the same Zuma who stole Okarun’s family jewel! The two of them team up to retrieve said jewel after Zuma drops it in enemy territory. Now they’ve got to fight some frogs and a giant chef to get it back. Meanwhile, in the outside world, Okarun clashes with Zuma’s friends over how best to rescue them!