Semi is cicada in Japanese.
The Haiku Master, Matsuo Basho had visited this valley and
wrote the same poem of Yamadera. "Shizukasa ya, Iwani
Shimiiru Seminokoe."
Semi Valley (蝉の渓谷) is a very unique valley located Namboku, Gunma. Because the rock of this valley is very weak, heavy rains crashes the bottom rocks. This is how this valley was made.
Tourist Info.
There is a parking and restroom.
Access
0. at Maebashi Station.
1. use JR Ryomo Line to Takasaki (15 min.)
2. use Joshin Line to Shimonita (1hr.)
3. use taxi to Seminokeikoku.
20 min
New Wave Samurai Movie. 
映画好き集まれ！ 
Semi is cicada in Japanese.
The Haiku Master, Matsuo Basho had visited this valley and
wrote the same poem of Yamadera. "Shizukasa ya, Iwani
Shimiiru Seminokoe."