Complete the following tasks to unlock the corresponding achievement.

Achievement	How to unlock
After School Ending	Saw the After School Ending.
Finished First Period	Cleared Chapter 1.
Finished Homeroom	Cleared Prologue.
Finished Second Period	Cleared Chapter 2.
Finished Third Period	Cleared Chapter 3.
Itsuki: Bad Ending	Saw Itsuki's Bad Ending.
Itsuki: Good Ending	Saw Itsuki's Good Ending.
Kaede: Bad Ending	Saw Kaede's Bad Ending.
Kaede: Good Ending	Saw Kaede's Good Ending.
Nao: Bad Ending	Saw Nao's Bad Ending.
Nao: Good Ending	Saw Nao's Good Ending.
Sakuya: Bad Ending	Saw Sakuya's Bad Ending.
Sakuya: Good Ending	Saw Sakuya's Good Ending.