Sumomomo Momomo Manga

From Yen Press: Momoko is the only child of the Kuzuryuu clan, a powerful martial arts family with inhuman strength. But strong as she is, her father fears a woman will never be able to master the skills of the family. Unless Momoko marries and bears a capable heir, the Kuzuryuu line is doomed to weaken and die off! With this mission in mind, Momoko is sent to the rival Inuzuka clan, where she is to marry the son of their mighty leader. But Koushi Inuzuka abandoned the martial arts long ago. Now committed to his legal studies, the last thing Koushi has on his mind is marriage — especially not to the world’s strongest bride!