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