A recent tweet from @evleaks states that a tablet with the model number LG V510 is indeed a Nexus tablet and it backs that up with what seems to be an inventory manifest which shows that the LG V510 is a Google device.
Seen it all before
Whatever it ends up being, a manual for the device, leaked by the Japanese site RBmen, suggests that its specs will be very similar to those of the LG G Pad 8.3, including in 8.3 inch 1920 x 1200 screen, 2GB of RAM, 16GB of storage, a 5MP rear camera, a 1.3MP front facing camera and a 4600 mAh battery.
The manual doesn't include the word 'Nexus' but it does state that the LG V510 will be running stock Android, which strongly suggests that it will be a Nexus device.
We're still waiting on a Nexus 10 refresh but in the meantime we'd quite happily take a Nexus 8 to tide us over, if that is indeed what this is.
Can't wait for the Nexus 8? Then check out the Nexus 7.