Here is the full list of all 13 Secrets of Me achievements.
Completed with "Ryunosuke" Good Ending.
Completed with All Endings.
Completed All Main Scenarios, Sequels, and Date Scenarios.
Completed with "Mizuki" Good Ending.
Completed with "Akira" Good Ending.
Completed with "Meguru" Good Ending.
Completed with "Shun" Good Ending.
Completed with "Akira" Best Ending.
Completed with "Meguru" Best Ending.
Completed with "Shun" Best Ending.
Completed with "Mizuki" Best Ending.
Completed with "Ryunosuke" Best Ending.
Completed the Prologue.