From Kodansha:
Since ancient times, the ninja and the yakuza have been at war, spilling blood around the world as empires rise and fall. So when, in the modern age, Shinoha, a ninja, meets Kiwami, a gangster following the path of the yakuza, the gokudo and discovers they have common interests, the obvious assumption is that nothing good can come of it. But can it be that one burgeoning bromance will shake up a 300-year grudge? Who will win the struggle for real ultimate power?