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.
Learn all of the battle spells.
Watch the Sucy Episode.
Watch the Akko Episode.
Watch the Lotte Episode.
Collect all volumes of Night Fall.
Obtain the Shooting Star Replica.
Earn the title of Laundry King in the Laundry King Championship.
Become the Queen of Spice in the Super-Spicy Showdown.
Complete the Ghost Witch and Last Nightmare.
Recover 18 Chariot Cards.
Complete the Time Demon and the Labyrinth.
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.
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.
Obtain the Mimosa Key and traverse the Mimosa Forest.