Here is the full list of all 24 Hentai Story Purple achievements.
Collect all pictures from Ruri
Assemble the first picture with Suzume
Collect all pictures from Suzume
Collect all pictures from Yoko
Assemble the first picture with Ruri
Collect all pictures from Satu
Assemble the first picture with Yoko
Collect all pictures from Oki
Assemble the first picture with Satu
Collect all pictures from Kasumi
Assemble the first picture with Oki
Collect all pictures from Chika
Assemble the first picture with Kasumi
Collect all pictures from Akiko
Assemble the first picture with Chika
Collect all pictures from Ishi
Assemble the first picture with Akiko
Collect all pictures from Suki
Assemble the first picture with Ishi
Collect all pictures from Riko
Assemble the first picture with Suki
Collect all pictures from Miyako
Assemble the first picture with Miyako
Assemble the first picture with Riko