Note: This game is also known as - Shadow Assault/Tenchu

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Neophyte (10 points): Finish Mission 1 without being spotted by anyone except Echigoya.
Apprentice (10 points): Finish Mission 28 without being discovered by anyone.
Footsoldier (10 points): Finish Mission 8 with at least 90 seconds left.
Genin (10 points): Finish Mission 21 with at least 60 seconds left.
Spy (15 points): Finish Mission 11 without taking any damage.
Chunin (15 points): Finish Mission 26 without taking any damage.
Oniwaban (15 points): Pull off a 15-hit combo (Solo Play).
Jonin (15 points): Pull off a 20-hit combo (Solo Play).
Veteran Ninja (20 points): Pull off a 25-hit combo (Solo Play).
Expert Ninja (20 points): Unlock Kagura.
Master Ninja (25 points): Unlock Onikage.
Legendary Ninja (35 points): Unlock all available characters.

Bonus characters - Successfully complete the indicated task to unlock the corresponding character:

Onikage: Successfully complete level 30 with Rikimaru.
Kagura: Successfully complete level 25 (defeat Shigi) with Tesshu.
Nasu: Successfully complete level 1 with Ayame.
Rin: Successfully complete level 1 with Rikimaru.
Tenrai: Successfully complete level 10 (defeat Tatsumaru) with Ayame.
Tesshu: Successfully complete level 20 (defeat Juzo) with Rin.