It looks like it [clarification: I mean the computer, Toshiba J-3100] was primarily marketed in Japan only, and moreover marketed primarily as a business laptop computer rather than home or gaming, so it's not surprising that many of us have never heard of it.
From Google search results, the
"Information Processing Society of Japan"'s "Computer Museum" website says J-3100 is just the Japanese model number for what's called the T-3100 outside of Japan. Google search on T3100 yields
this page with more technical specification details. Basically looks like it's an IBM-PC compatible laptop computer running MS-DOS 3.2
6.2 [edit: fixed typo] on an Intel 80286 CPU, with a display adapter that's fully CGA compatible (though it does appear to have a nonstandard special 640x400 mode, but I'm doubtful that the Lemmings software actually make use of that).
Given these spec details, I wonder if the game's software itself may just be the exact same version (or at best a barely modified version that, say, simply removed all non-applicable settings like choice of using VGA/EGA mode) of DOS Lemmings many of us owned, just packaged differently. Of course, for a collector, the different packaging boxes and manuals are still significant even if the software itself may not be actually different.
