Ryu begins his adventure by leaping off a waterfall and slaughtering his first Shadow Clan Ninja in a single strike. He pauses to reflect upon this one warrior's role in life, while Ayane, a member of the Mugen Tenshin, watches on. She oversees his progress and helps him throughout his adventure by providing him clues attached to Tulip Kunai scrolls.
There is a defector from the Hayabusa Clan, and his name is Murai. It is said that he is Ryu's uncle and leaves the Hayabusa Clan. Ninja clans don't take defection lightly, so it's assumed that Murai and the Shadow Ninja Clan that he creates are sworn enemies to the Hayabusa Clan. Most likely, it is because of this that Ryu slaughters the Shadow Clan with such abandon when Murai summons him. Halfway through his invasion of the Shadow Ninja Fortress, he attains the Fangs of the Samurai which give him access to the Inner Sanctum. Around this time Ayane says that she is leaving to check upon other matters, but that she will return later.
Since, Murai is Ryu's uncle (on his mother's side in all likelihood), Ryu simply ceases his onslaught once they fight to a draw in Murai's Inner Sanctum. What Murai says to entice Ryu to come to see him in the Shadow Ninja Fortress is unknown. Regardless, Murai and Ryu carry on a conversation where Murai inquires about the Dragon Sword and Dark Dragon Blade. Ryu seems both apprehensive about answering his questions and reserved when discussing his father's penchant with acquiring power. Murai comments how he is not of the Dragon Lineage, and so he is unconcerned with the affairs of the Dark Dragon Blade. At this point, Ayane interrupts their conversation with news of razing of Hayabusa Village.
Ayane is a member of the Mugen Tenshin Clan and practices Hajin Mon. It is apparent that she works for Murai, and it is possible that Murai uses her to summon Ryu. She seems either startled or compassionate at Ryu's presence in the Inner Sanctum despite the fact that she has been helping him with Kunai scrolls on his entire journey to the Shadow Clan's Inner Sanctum. From the Ninja Fortress's viewpoint, Hayabusa Village is clearly visible. It's evident that something is terribly wrong, as there is a large amount of smoke billowing up from the village. Ryu races back to the Village only to be put upon by the forces of Doku.