The Delinquent Housewife!, 1

A family comedy manga about a high school boy and his sister in law who moves in, who has a BIG secret from her past.
Tohru Komukai and his bride-to-be, Komugi, move in with his family just until they find a place of their own. Or, that was the plan, until Tohru suddenly leaves for a long-term business trip overseas, leaving Komugi to fend for herself on her in-laws' turf. While Komugi is pretty, considerate and appears to be an ideal housewife, the truth is she doesn't know how to do a lick of housework, and can't cook at all. Also, she has a secret past as a member of an all-girls bosozoku biker gang! The only member of the family to learn these secrets is Dai, Tohru's younger brother, and he helps Komugi keep up appearances until she can learn how to hold her own as a domestic goddess...