Sumomomo, Momomo Vol 1

Sumomomo, Momomo by Shinobu Ohtaka. An Action manga rated Older Teen, published in English by Yen Press.

Koushi Inuzuka is the heir to a legendary martial arts family, but he wants nothing to do with fighting and dreams of becoming a lawyer. Then Momoko Kuzuryu, a tiny but tremendously strong martial artist, shows up determined to marry him and give birth to the strongest heir of all.