The story behind this is that one day, Jax was testing out a teleporter with Shiro and Kenchi's assistance. As always with scenarios involving teleporters, something goes wrong, and the next thing they know Jax's body is mixed into Shiro and Kenchi's. They are now basically a huge furry clusterfuck, and it will probably take them at least a few years to get apart again, if they ever will.
By the way, this picture was done somewhat quickly, so I apologize for the lack of shading and how the hands look and such. This is not their permanent new design, but it is likely I will be drawing them like this again sometime.