"Tenchu 2: Birth of the Stealth Assassins is a prequel to the popular Tenchu: Stealth Assassins. It is a stealth game, produced by Massami Yamamoto, and directed by Takuma Endo, both of whom worked in their respective roles on Tenchu: Stealth Assassins. Both games were developed by Acquire and published by Activision, and appeared on the PlayStation.
The game is intended as a prequel to the original and depicts Rikimaru and Ayame as teens being taught by their elderly master named Shiunsai as well as another Azuma ninja named Tatsumaru and reveals how Rikumaru got the famous scar over his right eye
Source: Wikipedia, "Tenchu_2:_Birth_of_the_Stealth_Assassins," available under the CC-BY-SA License.