Issei is back with Rias and Asia living in his house, and Kiba starts acting weird when he sees a picture of a holy sword at Issei's house.

Summer break is coming up fast for Hyodo Issei, but all his plans are put on hold when he finds out he is to accompany Rias for her visit back home to the underworld! A new adventure is about to begin and all the while Koneko is not acting herself.