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.
Red Temple Of Nara
On The Road To Enlightenment
Urabandai Lakes
Himeji Castle
Torii
Komainu No Osaka
Pull It OUT!
Zen Garden
Stop The Pop... With A FIsh
All Puzzles Complete!
A Mind In Training
Consciousness Raised
Enlightenment Attained
Osaka Castle
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