An official form from a person (Japanese or non-Japanese) residing legally in Japan, working full time if possible or clearly able to demonstrate sufficient assets to support you in case of need This letter states that they agree to be legally, morally and financially responsible for you while you are in Japan Form in Japanese is here
Undertaking, usually on the part of a bank, either to fulfill the obligations of another party (see "ancillary guarantee") or to pay a specified amount of money upon presentation of specified documents stating that the party being guaranteed has defaulted on certain obligations (see "demand guarantee") One must be careful to discern which type of guarantee one is dealing with as they both require presentation of documents but work very differently thereafter
A letter from a bank to a brokerage firm which states that a customer (who has written a call option) does indeed own the underlying stock and the bank will guarantee delivery if the call is assigned Thus the call can be considered covered Not all brokerage firms accept letters of guarantee Also: letter issued to O C C by member firms covering a guarantee of any trades made by one of its customers, (a trader or broker on the exchange floor)