From MangaHelpers:
Rai has now forged a new empire and has ushered in an era of peace. With his Empress Reila, he has heirs to continue his legacy. However, a group of pirates has been threatening the peace of the empire. This group of pirates is led by a powerful young man who claims to be the child of Masamune, and who has been raised by barbarians. The young pirate does not know the identity of his father, but he is determined to exceed him and to bring down the empire. Ryuga Rai must find some way to deal with the situation, both to protect his empire and because he knows that he is actually the young rebel's father.