Diabolik Lovers: The Fiancée (Shu X OC)

Roka Igarashi is the betrothed of Shu Sakamaki. She's known the Sakamaki siblings since childhood due to their families' connections. Devoted to Shu, she'll do anything to keep him to herself. She hates all the sacrificial brides and when she learned that a new one will be arriving, and that the brothers are not allowed to kill her, she makes sure to keep her in place like she did with the others. She'll meet Yui, first suspicious of her purpose, will she warm up to her as they live under the same roof? And what is her relationship with the other Sakamaki brothers?