Japanese Hammer or Genno / Gennou (玄能)
Japanese hammers known as Genno (or Gennou) are a specialist style of hammers. The head of the hammer is made of a singular type of steel that is designed to absorb the impact of the hammer strike. They have a white oak handle and are very well balanced which makes using them quite easy.
The Genno generally has two faces on the octagonal head, one is a flat face and the opposing face is slightly convex. The flat face is used for hammering nails, striking Nomi (Japanese chisels) and setting the blade of Kanna (Japanese woodworking planes). The convex face is generally used for hammering smaller nails with the convex head aiding in avoiding damage to the surrounding timber.