>NG4 final boss is the True Dark Dragon
>Yakumo acknowledges that the True Dark Dragon's awakening and Seori's death are his fault
>To make things right, Yakumo sacrifices himself to form a Dark Dragon Blade forged from his own blood
>Ryu wields the Yakumo Dark Dragon Blade against the True Dark Dragon
>Their battle shakes heaven and Earth. The city is being torn apart from Ryu's and the Dark Dragon's power
>Ryu is on the backfoot. The spirits of Yakumo and Seori cheer him on from the afterlife.
>Ryu, more determined than ever, takes off his mask. He has short hair, showing that he's lived through the NES games and is at the height of his power.
>The final blow is Ryu with the TDS and Yakumo's spirit wielding True Dark Dragon Sword killing the dragon once and for all.
>Ending happens. Yakumo's spirit now wears white ceremonial garb, his hair is fully white, and he crosses the afterlife with Seori. They're both holding hands and they say goodbye to Ryu.
>Ryu is the last man standing in NG4. Everyone is dead, so he turns into a hawk and flies away.
>Post-credits scene. World leaders have feared that the Hayabusa Clan has become too powerful as it controls the True Dragon Sword, The Dark Dragon Sword, has several ninja on the level of Kenji who are powerful enough to be Master Ninja in other clans, have subjugated the Raven and Black Spider Clans and is lead by the strongest man on the planet, Ryu Hayabusa. They have the power to topple any country.
>There is one remaining clan that could oppose the Hayabusa Clan and it has the second ninja to achieve master ninja
>CIA agents enter a familiar village
>"Are you the Master Ninja, Hayate?"
>"Ah... Ninja are masters of DECIET. For political reasons, I carry the title of Master Ninja for the one who truly wields that power is over there."
>A young woman in a kimono opens her eyes...
>Ninja Gaiden Episode 5: Two Masters