The transparency of the players is not synched between clients

[Mimigris]

If the sprite of a player is listed as being transparent, it will only be the case on the screen of the player being transparent, not on the screens of the other players.

In Yume Nikki, by using the Spirit Headband effect, the player become transparent.

Here's how it is displayed on the screen of the player using it:

And here's how the player using said effect is displayed on the screen of the other player (the other player is not transparent):