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