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