The Toshiba N554 mouse is a Bluetooth mouse based on the Broadcom BCM2042 chipset.
Some information gathered on the net about this chipset:
A Bluetooth mouse reference design using the BCM92042MDX-B88 module
A different mouse reference design with more details, a BOM and PCB layout images
The Toshiba mouse seems to use this particular module, at least the layout looks very similar.