Here is the full list of all 26 Magical Diary Demo achievements.
You received detention.
You received five detentions in one game.
You refused to attend any classes!
Too many demerits ended your school year.
You maxed out your Stress.
You maxed out your Merits.
You maxed out your Cute.
You maxed out your Weird.
You won the election for class treasurer.
You became a full member of the Rose and Wasp.
You retrieved the elusive stuffed bunny.
Oops! Accidentally married.
Someone has locked lips with you.
After a year locked in the school dungeons. Nasty.
You helped Ellen form a school conspiracy.
You had an escort for the May Day Ball.
You made it through the school year!
You maxed out your Red Magic.
You maxed out your Blue Magic.
You maxed out your Green Magic.
You maxed out your Black Magic.
You maxed out your White Magic.
You maxed out your strength.
You maxed out your smarts.
You broke your oath and lost your magic - for now.
You can't go home again.