How did the whole fake body double thing happen? And how the hell did Sae not realize she was in the Metaverse?

Rank the protagonists! Which protagonists is the strongest and why? And how do the others add up against them? <br> 1. Naoya <br> 2. Tatsuya <br> 3. Maya <br> 4. Minato <br> 5. Yu <br> 6. Akira