Here is the full list of all 30 How To Date A Magical Girl achievements.
View Rei's secret event
Complete Rei's route
View Kaori's secret event
Complete Kaori's route
View Miyu's secret event
Complete Miyu's route
View Yui's secret event
Complete Yui's route
Reject a girl's confession
See the Mystery Ending
See the Happy Ending
See the Bad Ending
Drink a potion
View Hikari's secret event
Complete Hikari's route
View Rei's friendship event
View Yui's friendship event
View Kaori's friendship event
View Miyu's friendship event
View Hikari's friendship event
Get an A grade in all key attributes
Win a prize at the arcade
Get an A grade in Magic
Get an A grade in Alchemy
Play with Hoshi
Get an A grade in Perception
Get an A grade in Expertise
Finish reading 6 books
Give a gift to a girl
Start out life as a Liar