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