The Proprietor

The Proprietor of Vintners' has never been seen or heard in public. They run, and appear to own, the island restaurant and communicate with the world exclusively through their senior staff.
On rare occassions, devotees (Vintner's term for guests) have seen a shdowy figure in the darkened upper tiers of the restaurant or through a frosted or stained glass window and it is assumed that this is the Proprietor. When seen as such, they have no discernable features - even their species and sex are unknown.
The two most popular theories about the Proprietor are that they are either a ghost or a zoshuku, but there is no eveidence for or against either theory.
Staff at Vintners' are bound to secrecy, and this appears to extend to the Proprietor as much as it does to the devotees - either nobody has seen them, or nobody will admit to seeing them. This secrecy is a blend of a magical binding, prohibiting people from gossiping about who and what they've seen while working, and a financial one - Vintners' staff are paid extremely well and the wealthy devotees are encouraged to make generous donations, which are then divided among the staff as a gratuity. Whether unable to speak or unwilling to risk a good thing, the staff remain silent.
Administrative efforts to identify the Proprietor have met with frustration - the island sits just outside Thsúntos' city limits, was never incorporated into the city charter, and as never been bought or sold, so does not appear in any land records. It is known to have been owned and occupied by a religious order that dissolved at some point in the late 5.600s. The island remained unihabited until 5.763, when talks about expanding the city and redeveloping the site were forced to a halt by construction unexpectedly begining on what is now Vintners'. The local firms contracted to do the work were contacted by letter and paid in cash.