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