background – Writing around an un-defined character

I am planning to attend a LARP set in Rokugan – when (and if) that happens. It’s a rather story- and character-play-heavy setup with little to no combat planned.

Now, I have already a character with some cliff notes established and approved by the organization crew, and I want to write out some of that backstory in some sort of travel log. What my cliff notes show is that the character is a Kakita Duellist. During the Clan War they have served as a Yojimbo to a certain person which was given a possible placeholder name, yet that wasn’t confirmed or logged in yet.

That certain person is only known to have served as an envoy for the crane during the clan war, nothing other is dished out – and as there are no NPCs planned, that character might be filled with another player. That means I can’t define stuff about that certain person of rank without talking to the organizers or that other player… which gets to the problem that the certain person is just a placeholder for any player that might want to be a Crane with a courtier background. And at the current point, that is an unfilled position.

I guess I might refer to them as a certain person as it happens in translations of Japanese literature for an unknown person or person that can’t be mentioned for any reason, but that technique might be hard with the cliff-note that my character: They were a certain person’s guard for about 5 years and have traveled quite a lot of Rokugan in that time. Which is the timeframe I actually want to write about.

How could I refer to that undefined (and for me undefinable) certain Character in a way that doesn’t make the resulting narrative unreadable or establishing cliff notes that might conflict with what the future player of that certain Character might want?