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