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