Kaoru Ise serves in the Imperial Japanese Army's reserve corps under Captain Tatebayashi Kai. Visually distinguished by an eye patch, he is the twin brother of Kahoru Ise, and both siblings exhibit absolute loyalty to their captain.

During a supernatural event affecting multiple individuals, Kaoru undergoes a physical transformation into a smaller, cuter form alongside his brother and Tatebayashi, all while maintaining their military commitment. Within the army, Kaoru wields the ability to manipulate deceased spirits, deploying this power during confrontations with factions like the Five Katana.

Expanded media features Kaoru sharing narrative routes with his twin, encountering protagonist Hiiragi Kyoichiro in scenarios beyond combat. These routes maintain his core traits of loyalty and intensity, with certain paths depicting extreme actions, including violence towards Kyoichirou when orders clash with personal connections.

Kaoru's role consistently emphasizes his position within the military structure and his unshakeable bond with his twin. Their actions remain aligned with Tatebayashi's objectives, whether conducting patrols, engaging supernatural entities, or navigating internal army debates over the ethical use of spiritual powers.