Here is the full list of all 26 Pixel Puzzles: Japan achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
All Puzzles Complete!
Tsukubai
Enlightenment Attained
Gardens of Nijo Palace
Himeji Castle Gatehouse
Akai Hashi
Temple Lanterns
Consciousness Raised
Butsudan
Cherry Blossom Over Water
Hiroshima Castle Gatehouse
Osaka Castle
Nara Temple Gates
A Mind In Training
Komainu No Enryakuji
Iwakuni Bridge
Koen
Himeji Castle
On The Road To Enlightenment
Urabandai Lakes
Torii
Red Temple Of Nara
Komainu No Osaka
Zen Garden
Stop The Pop... With A FIsh
Pull It OUT!