This is a three-dimensional masyu puzzle.1 The five squares depict the layers of a $5\times5\times5$ cube. The goal is to make a single loop in 3D space which fulfills the following properties:
- The line passes through centres of cells and makes 90-degree turns only.
- The line cannot cross itself or branch off in multiple directions.
- The line passes through every white and black circle.
- When passing through a white circle, the line must go straight through the circled cell and make a turn directly before or after that cell (or both).
- When passing through a black circle, the line must make a turn in the circled cell and continue straight for at least one cell on both sides.
Note: Feel free to use any notation you feel most comfortable with in your answer, as long as it's properly explained. As an example, I like to mark movement between levels with diagonal lines as shown below.