Look at the back and find the place where the round back plate is just a little wider. This part of the back plate overhangs the watch case a little. Using a sharp thin instrument, get it under this wider part. Prise the back off, levering it up and away from the case. It does not need to be rotated in the direction of the watch dial because there is no screw thread. A good choice of tool is a small "jeweller's" screwdriver but a sharp small knife, edge on may work.
The battery is removed in a similar way but it does not have the widening of the plate that is a feature of the watch.
KNBD, September 2014
