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 Michiko ending.
Completed friendship ending.
Chose to let Saori have Takeo to herself.
Completed Takeo ending.
Completed Keisuke ending.
Completed Yuri ending.
Took car to school.
Walked to school.