Uchi-bukuro

Uchi-bukuro a type of Japanese attire employed by the samurai class primarily around the Sengoku period (16th century) of Japan. The Uchi-bukuro translated as a money purse that was usually carried at the waist or around the neck. These ways are known as being rather inconvenient however. The best known why within feudal Japan when it comes to carrying money is to paste old Japanese coins onto a folded strip of thick paper, and then put it between the collars of the under area of your armor.

References

"The Samurai Sourcebook"