The other thing with names is that the character names displayed in battle (Yugiri Mistwalker, Oboro Moonrise, etc.) are not surnames but epithets - and the same is done for Eorzean characters. (eg. Haurchefant's surname is Greystone but he will be "Haurchefant of the Silver Fuller" in battle instances.)

The lorebook lists both surname and epithet for job-quest characters. So from that, the ninja quest characters' full names are Oboro Torioi and Karasu Kanshi.

Lorebook volume 2 will probably list the proper surnames for Yugiri and Gosetsu.