Here is the full list of all 10 Sakura Agent achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Unlock all of Kimiko's scenes.
Working hard while patrolling the beach.
Fail to stop someone from falling.
Unlock all of Masumi's scenes.
Unlock all of Masumi's and Kimiko's shared scenes.
Win a poker game.
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Put an end to the invasion.
Unlock all images in the gallery.
Complete your first mission.