Semicircle Bathroom with a Niche?

Hi all, need some advice and ideas on how to renovate our newly bought home! My wife is looking to renovate the bathroom to include a niche however, we are complicated by 2 things

1. The shower area is in a semi circle shaped

2. The walls of the bath area is tiled with mosaic tiles (quite arty) and we would like to keep them.

Below is a picture of how the bathroom looks like (grabbed from the web)

As we would like to keep the current mosaic tiles (and also to keep cost low) that means we will not be hacking the walls.

Does anyone have any ideas on trying to incorporate a niche into the shower area? Some ideas that has been floated by the IDs are to build a wall along the glass panel with a niche but I'm concern it will darken the toilet and also make it look more claustrophobic.

Any ideas will be much appreciated!