I am fairly certain that what you are referring to as the "landers" are actually just cases for the rovers. MINERVA stands for "MIcro-Nano Experimental Robot Vehicle for the Asteroid". Note that its name only talks about rovers.
If you take a look at this picture (courtesy Sky and Telescope Magazine), you can see that the rovers are contained within a more or less empty shell.
Spaceflight101 has a good article which details how MINERVA-II will actually work. In particular, it says
Communications with the Hayabusa spacecraft are accomplished at data rates of up to 9,600 bits per second.
This abstract I found also says
They fall into the asteroid surface captured by the weak
gravity and then start the autonomous exploration when the obtained data are transmitted to the relay
module on the mother spacecraft
Based on this and other pictures I found, I think it's safe to conclude that the rovers will communicate directly with the spacecraft, not with any lander.
On a side note, I found a scientific paper discussing the mechanics of how the rovers will get around by "hopping" on the asteroid's surface.