The mamushi (Gloydius blomhoffii) is the most dangerous snake in Japan. Approximately 2,000~3,000 people get bitten by these snakes, and approximately 10 people die every year because of the snakes’ venom. (See Wikipedia)
The mamushi is also called the Japanese pit viper.
The color of these snakes are mostly brown, and they have diamond shaped heads. We have these snakes around the neighborhood in warm seasons. We’d better be careful!
The Okinawan habu, from Okinawa, is also very dangerous. This snake and the mamushi are the most venomous snakes in Japan. (Other snakes include the yamakagashi, himehabu, etc.)