The version of the LS-120 sold by Dell supported Japanese Mode 3 on a 3.5" floppy (or 1.2MB capacity). See http://support.dell.com/support/edocs/storage/8359t/en/specs.htm for proof. I expect that some other variations of the LS-120 also supported 1.2MB mode but might not mention it in manuals targeted outside Japan. No 5.25" drive needed. I suspect the data cable adapter may have been included by mistake instead of a molex to 3.5" power adapter cable.