If you're looking for manga similar to Rashanu!, you might like these titles.
In the ancient House of Nekogami, sibling rivalry is a game of life and death. The patriarch of the Nekogami family is dead, and his grandson Sukekiyo is the rightful heir. There is just one problem--Sukekiyo is away at war, whereabouts unknown. Only one person can inherit the fortune, and the triplets, Yoki, Koto, and Kiku, aren't going to let Sukekiyo's fiancee, Tamayo, walk off with prize. With a fortune at stake, it's kill or be killed as the Nekogami family goes up against demons, thieves, and each other to protect the family... and the cash!
Nicknamed “The Prude,” Aizome Maiko is a misunderstood girl who actually has explicit fantasies. When a boy with a delinquent’s face, Yajima Keisuke, ruins her dream romantic encounter, she forces him into slavery by getting him to carry out her ridiculous plan to reach the man of her dreams. What has “The Prude” have in store for Yajima and will her ridiculous plan succeed?