Here is the full list of all 25 Little Witch Academia: Chamber of Time achievements.
Collect all of the room decorations.
Watch the Diana Episode.
Watch the Jasminka Episode.
Watch the Constanze Episode.
Watch the Amanda Episode.
Watch the Sucy Episode.
Watch the Lotte Episode.
Watch the Akko Episode.
Complete the Ghost Witch and Last Nightmare.
Recover 18 Chariot Cards.
Learn all of the battle spells.
Obtain the Shooting Star Replica.
Complete the Time Demon and the Labyrinth.
Collect all volumes of Night Fall.
Obtain the Pollux Key and traverse the Labyrinth of Pollux.
Obtain the journalism club microphone.
Complete the Hourglass of Fire and Ice.
Obtain the Gienah Key and traverse the Gienah Tundra.
Earn the title of Laundry King in the Laundry King Championship.
Obtain the Shaula Key and traverse the Shaula Desert.
Obtain the Regulus Key and traverse the Regulus Mines.
Complete the Guard Dog and the Pendulum.
Obtain the Ankaa Key and traverse Mt. Ankaa.
Become the Queen of Spice in the Super-Spicy Showdown.
Obtain the Mimosa Key and traverse the Mimosa Forest.