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
Himeji Castle Gatehouse
Akai Hashi
Gardens of Nijo Palace
Hiroshima Castle Gatehouse
Consciousness Raised
Butsudan
Temple Lanterns
Cherry Blossom Over Water
Nara Temple Gates
Iwakuni Bridge
A Mind In Training
Komainu No Enryakuji
Osaka Castle
Torii
Koen
On The Road To Enlightenment
Urabandai Lakes
Himeji Castle
Red Temple Of Nara
Komainu No Osaka
Stop The Pop... With A FIsh
Zen Garden
Pull It OUT!