Here is the full list of all 26 Nightshade achievements.
Unlocked Goemon Route
Bad ending with Chojiro
Happy ending with Chojiro
Unlocked Chojiro Route
Unlocked all Achievements
Completed all CG graphics
Completed all Endings
Completed all Memoirs
Completed all Movies
Unlocked all CG's with Gekkamaru
Unlocked all CG's with Kuroyuki
Unlocked all CG's with Chojiro
Unlocked all CG's with Hanzo
Unlocked all CG's with Goemon
Unlocked all CG's of Koga
Unlocked Gekkamaru Route
Unlocked Kuroyuki Route
Unlocked Hanzo Route
Happy ending with Gekkamaru
Bad ending with Gekkamaru
Happy ending with Kuroyuki
Bad ending with Kuroyuki
Happy ending with Hanzo
Bad ending with Hanzo
Happy ending with Goemon
Bad ending with Goemon