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