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