Love letter Bicycle playing cards

Koibumi (lit. love letter) is a letter or an epistolary poem. While nowadays letters are put in envelopes, in the past they were tied with a string. Therefore, the family crest representing a letter is designed in the shape of a letter tied with a string. Most basic letter crests are designed in the shape of a long, thin piece of paper folded and tied at the middle, either into a ball or a 'ku' shape. Some crests, like 'koibumi-mon', have a kanzashi hairpin added to the design (according to 'All About Family Crests' by Takasawa).