It is located on the Oide River.
Otaki Falls and Kotaki Falls (大滝・小滝) are twin waterfalls located in Rikuzentakata. They are small but very powerful waterfalls.
Tourist Info.
There is no parking.
Access
0. at Ichinoseki Station.
1. use direct bus to Rikuzentakata.
2. walk west (2hr.)
10 min
New Wave Samurai Movie. 
映画好き集まれ！ 
It is located on the Oide River.