How to get every costume for Mita and their locations.

Other than default, there is three more cloths you can get for Mita.

School

After meeting Mita for the first time and while checking around the house with her, you can find the school suit hanging on side of the closet next to bathroom door.

Vampire

In She Just Wants to Sleep chapter with Sleepy Mita go to kitchen to find some pumpkins on the table.

Solving the Pumpkins Puzzle will reward you the Vampire suit. Click on the pumpkins and then light them up in this order from left to right (you need to light up all of them):

1. Fourth

2. Second

3. Third

4. First

5. Fifth

Christmas

Winning Penguin game in Things Get Weird chapter for two times will reward you the Christmas suit.