Just in case you want something- I've compiled a list of about 1800 male Japanese and Korean names and about 750 female names (inlcuding some L5R ones) (sadly the lists I found were far shorter for females. The Korean names are a little more unusual, so in the master list they are green, but sadly I can't get that to carry across in the randomised list.
I've put them together with a randomiser that will generate 20 male and 20 female names, some random Major Clan, Minor Clan, Vassal Clan and Imperial Families family names as well as giving you a suggestion (e.g. Female 14, Major 3= pick the 14th Female name and 3rd Major clan family) if you want it.
I've only used families and clans that were in existance at the beginning of Alderac's timeline, so generally this can be used for anyone, though some of the Vassal and Minor families might not be relevant for you. You will need to run Macros in Excel if you want the button to work.