Hmm, the odd connector on the PCMCIA card is the same as the one for the IBM Portable Stereo CD-ROM drive - you can see it sort of in this picture from when I got the big boxed version: Re: Bought these (retro) hardware today
Looking up the Panasonic card part number lead me to this: https://ameblo.jp/tom-photo-life/entry-12480816223.html
Using google to translate, it says that Panasonic actually made all the ATAPI PCMCIA cards back then? And it seems the IBM drive worked with the panaonic card + cable?

Still though, that's only part of it, the ATAPI card would be one part of the driver then the device at the other end would be another, so you probably can't use IBM drivers.
The Panasonic site does say that windows 98 was supported with your PD/CD drive, maybe there are some later ones around.

Hmm I have a Panasonic KXL-D740 (ext CDROM + PCMCIA card) and had to search up some Win9x drivers a decade or so ago, it is scsi but somewhat similar combo of Pana Ext.CDROM and Card.
Will go check my archives to see where I got them (hope I left notes) ...Maybe there are some Win98 drivers for LF-UC15/LF-1500 but doubt there be XP drivers...never found for the D740...

added: This is the pana archive and no listing for your device I could find: (note my 740 is listed).
cdrom: http://web.archive.org/web/19991008145115fw_/ … vers-cdrom.html
and http://web.archive.org/web/20000301144209fw_/ … vers-cdrom.html
pd: http://web.archive.org/web/19991113191924fw_/ … ivers-misc.html

Being an OEM drive for IBM their archives may be the only place to find Win98 drivers if there are any. I did find a set from 1997 that mention Win98 in the posting but not in the drivers...

I could not find the drivers on the archived panasonic web sites, unfortunately.
In my experience win95 drivers usually work in Win98. Did you try to edit the relevant INF file? There is a section "version" right in the beginning. Is it "windows 95" or $Chicago$ there? $Chicago$ should work on win98 as well.

The drive is completely new. Nobody touched it from the day it was produced...
And... I found the original floppy disk in a sealed envelope deep in the drive original box. Includes soft only for w98. I checked it and it works.
I will upload a floppy image of this LFUC15 pcmcia interface

EDIT:
Driver provider is IBM...

Nice ! That is about the same as this: http://www.storagedrivers.com/drivers/126/126210.htm
If I would have known could have pointed to Deksors archive, it has the storage drivers file. It has the same readme.txt in Japanese.
Attached below for comparison...

Horun wrote on 2022-09-28, 21:53:

Nice ! That is about the same as this: http://www.storagedrivers.com/drivers/126/126210.htm
If I would have known could have pointed to Deksors archive, it has the storage drivers file. It has the same readme.txt in Japanese.
Attached below for comparison...

Look like the same... Only difference is extra L_option.reg file