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