礼金

Etymology
Compound of. First cited in 1678.

Noun

 * 1)   key money: an amount of money paid to a landlord to start a lease agreement, usually non-refundable and separate from the deposit, and often a set multiple of the monthly rent amount
 * 2)  an amount of money given as thanks for something
 * 1)  an amount of money given as thanks for something

Usage notes
The custom of a non-refundable gift of reikin or key money to start a lease is more common in eastern Japan than in western Japan. See for more details.