Here is the full list of all 9 Last Days of Spring Visual Novel achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Completed all endings.
Completed Yuri ending.
Completed Takeo ending.
Completed Michiko ending.
Chose to let Saori have Takeo to herself.
Completed friendship ending.
Completed Keisuke ending.
Took car to school.
Walked to school.