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