天辺の穴 Tenpen no Ana

What is Tenpen no Ana of Samurai Armor?

The term "Tenpen no Ana" refers to a hole at the top of a helmet (Kabuto). During the Heian to Kamakura periods, this hole was used to let out the topknot (Motodori: hair tied up on top of the head) wrapped in an Eboshi (a type of headgear). This was done to stabilize the helmet when worn. After that, the hole became smaller and is said to have been left for ventilation. It can be seen mainly in Hoshi Kabuto (star helmet), Suji kabuto (muscle helmet), and also in Zunari Kabuto (head-shaped helmet), Toppai Narikabuto (protruding helmet), and others.

See more terms related to samurai armor in this samurai armor glossary

Samurai armor parts explained

Samurai armor history and types