I'm in Love with the Villainess manga volume 6 features story by Inori and art by Aonoshimo.

Rae is delighted when Claire decides to spend summer vacation in Rae’s hometown of Euclid. She’s extra delighted when she gets to see Claire in a swimsuit! But their fun is cut short when a ghost ship drifts into the harbor crewed by the undead! The girls will need to use their magical abilities to protect the city, but they soon realize that there is a traitor close to them! Can Rae figure out who it is in time?!