The truth of Ninja -Ninja Encyclopedia-

Kiki-Zutsu

Ninja eavesdrops with "Kiki-Zutsu"

During childhood, did you have an experience of playing with a string telephone? It was fun hearing the voice of the other person echoing in the paper cup. The sound that vibrates from the string is very low and in spite of this, the voice from the other person amplifies on a large scale. The principle of the equipment is that the soundwave from the string amplifies in the paper cup by means of resonating thousands of times in the narrow space. " Kiki-Zutsu () ", was a kind of bug used by ninjas, it was a tool used make use of this natural phenomenon. The shape of kiki-zutsu was quite simple. Kiki-Zutsu was an extendable pipe made from brass alloy. Its size was 35-158 mm and its diameter was 60-70 mm. In those days in Japan, it was really silent at night because there was a lot less noise around.
Japanese houses in those days were wooden and in the house, partitions were only made from bran so the sound echoed well. Accordingly, when ninjas put kiki-zutsu on a wall or door, ninjas could pick up the conversation from the house easily. Ninjas could also confirm whether their enemy was sleeping or not by means of checking whether they were snoring. As well as kiki-zutsu, ninjas had " shinobi-zutsu (Eѓ) " with them on their missions. Although ninjas were kind of supermen, they would cough if staying in a cold space for a long time just like any normal person. When doing so, they would spit or cough into the shinobi-zutsu, which was a wooden pipe as this would mask the sound keeping them unheard.
Kiki-zutsu could also be used as a megaphone. Ninjas did not necessarily accomplish their mission by themselves always, as there could be teamwork involved. In such situations, the conveyance of information was valued. The skill of communicating was called " Dentatsu-jutsu (`Bp) ". Using a kiki-zutsu as a megaphone was one of the techniques.
It was the most important thing for ninjas to transmit the correct information to their lords whether to one or multiple people.