A small ceramic cup for drinking Sake. Using it to make an offering at a shrine in the Abyss will summon a Visitor. You can offer up to two of these at a time, and one cup will summon one Visitor. When a Visitor arrives, it will take one the cups.
While white is a symbol of purity that cannot be tainted, it is also the colour used for burial clothes and can thus represent death and departing from the mortal realm.