Dandadan. Volume 13: 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!
It is revealed that Vamola, the girl found inside the kaiju suit, is actually a member of the once thriving Sumerian race from deep space! Unfortunately, her home world was attacked by the aliens presently targeting Earth, leaving her people scattered. She herself had been forced to plot her escape from the planet with a group of other women—including Banga, who found her as a child and raised her. Now, having learned of Vamola’s past, Momo and the others rise to action, but the aliens they face are a formidable enemy.