Synopsis: SLASH/DOG

Taking place in the identical realm as High School DxD albeit long before its incidents, the plot revolves around Tobio Ikuse, a high schooler who is still grappling with an event that resulted in the vanishing of his childhood companions. He encounters formidable creatures called "Utsusemi" one day, but his former lost buddy, Natsume, comes to his rescue. Alongside Natsume and a girl named Vali, he endeavors to uncover the reasons behind his friends' disappearance.