Oops, I got Matsushita mixed up with Mitsubishi, although I did know that Panasonic is a division (or brand name) of Matsushita.
So my question should be, doesn't Mitsubishi also make NiMH battery packs for Toyota?
I doubt it. I believe Toyota's NiMH battery pack suppliers are Panasonic EV and Denso (Toyota holds equity in both companies). Mitsubishi supplies inverters for Toyota hybrids.