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