Here is the full list of all 54 Campus Notes - there are forget me not. achievements.
Decided not to ask how Shion feels
Unlocked all achievements
Spent quality time with Shion
Saw all event CG's
Spent quality time with Togi
Completed Ending: True route, solved IMA
Reunited with everyone in the real world
Spent quality time with Kaen
Chose to do everything from the start
Met Niko
Found out Fuma couldn't get to Akihabara
Met Takuma and found out he didn't own a phone
Called mom and found out about the time difference
Chose Fuma
Completed Ending: Shion's route
Had a date with Shion
Talked with Shion
Chose to make a phone call
Chose to fight IMA
Completed Ending: Kaen's route
Talked with Togi and Kaen
Talked with Kaen and Shion
Followed Fuma
Agreed with Kaen
Chose to believe in a curse
Talked with Kaen
Chose to leave the phone
Chose to go home
Completed Ending: Togi's route
Found out the truth……?
Tried eavesdropping Fuma and Shion
Asked to know how Shion feels
Walked the Botanical Garden with Shion
Talked with Shion and Togi
Reunited with Shion at the Botanical Garden
Really, it's not a date
Disagreed with Kaen
Chose to believe in a bond
A feast on Inago and Bee larvae
Went to Kumano shrine
Talked with Togi
Went to Ichinoya Yasaka shrine
Went to Saiki shrine
Promised to meet Aika again
Chose to deliver the phone
Joined Bertha's Knights
Went after Kaen
Chose not to choose
Idiopathic Mass Amnesia
Reunited with the three heroines
Met the girl with silver hair
Met the three heroines
Made a friend
Started the game