Answer
The answer is as follows. 
Katrielle and the Millionaires' Conspiracy walkthrough
Puzzle Location: Prologue
The letter 'K' has fallen down from the sign above the cake shop.
Use the three triangles to make the letter 'K' inside the box.
You can move the triangles around by sliding them, and you can rotate them by touching them.
When the 'K' is formed, the success message will be displayed automatically.
Place the triangles carefully.
All of the triangles need to be rotated.
Place the big triangle right up against the right-hand edge of the box.
If there is a gap, you will not be able to correctly from the 'K'.
You don't need to use the three panels to from the 'K'.
Arrange the panels so that the entire box looks like it contains a 'K'.
Place one of the small triangles right at the top and the other right at the bottom.
Then you just need to adjust their position so that the thickness of the letter looks correct.
The gaps between the panels should show the shape of a 'K'.
The answer is as follows.