My Happy Marriage, Vol. 4 (light novel) by Akumi Agitogi, Tsukiho Tsukioka

CAUGHT BETWEEN FRIEND AND FOE… On their trip home from the Kudou family villa, Miyo and Kiyoka narrowly escape an ambush from the leader of the Gifted Communion, Naoshi Usui, who claims to be Miyo’s father. Fearing that Miyo will be targeted again, Kiyoka insists that she accompany him to his workplace from now on and appoints a female soldier named Kaoruko as her bodyguard. Though Miyo is unsettled by the revelation that Kaoruko was one of Kiyoka’s previous marriage candidates, the two women gradually warmup to each other and become friends. But can their bond survive the hidden threat coming for Miyo…?