Even in its hardware form, 1988's Kawai K1 - often viewed as decidedly low-budget alternative to Roland’s all-conquering D-50 - was more ROMpler than full-on synth, being a collection of multisampled instruments with relatively few hands-on editing options. So, it stands to reason that a software plugin version should be pretty authentic.
Nils Schneider’s K1v is precisely that; released to a warm reception earlier this year, this is now available not only for PC, but also Mac and Linux
K1v promises to accurately emulate the K1’s 8-bit synthesis engine and parameters, and includes 768 presets (that’s the factory bank and all the ROM cards). You can import and export SysEx presets and banks to/from the original keyboard, and you can also use the K1v as a software editor for said hardware.
You can download K1v for free from the Nils Schneider website; be sure to support the developer by donating if you like it. It's available in 32-bit and 64-bit versions for Windows, Linux and macOS, and in VST2.4/AU formats