There are several typical ninja codes that used rice, stones and rope. Rice was dyed 5 colours (blue, yellow, red, black and purple), then using different combinations of colours and arrangements it is said that over 100 different kinds of codes were created. There was no fear that the dyed rice would be eaten by insects or birds. Stones could also be placed by the side of the road in pre-determined positions as a means of communication with an associate. A knotted rope, or 'yuinawa', could also convey a ninja's whereabouts or destination to an associate, both through the number of knots and the way in which they were tied. If they needed to convey more complex information, ninja wrote letters using coded symbols that only one of their group would understand, such as the 'Shinobi-iroha', or 'Jindaimoji'. Shinobi-iroha: This was a series of 48 characters based upon a combination of 14 kanji （木・火・土・金・水・人・身・色・青・黄・赤・白・黒・紫） that could only be read using special rules. Jindaimoji: This was a system of ancient Japanese kanji that were used in Japan before Chinese characters were imported, but were all but forgotten along with the introduction of the Chinese kanji. Often, characters were written on paper using the juice of a mikan (Japanese mandarin orange), and when the juice dried the message became invisible. When held over a charcoal fire, the writing emerged once again in a process known as 'aburidashi'.
