what exactly are those passenger tokens

[Kurtz]

i got a few ones and i found it quite curious, is it something like a backstarter item? i got one called shiyangyue and a few one that i recycled already, do you get a secret achievement for getting it all?

[Seisachtheia]

Nope. They're just there to be recycled for jin. They do give a little extra backstory and emotional grounding for what is happening in the Empyrean District.