The organization lists the first of their three main objectives as:
1) Prevention of nuclear war and the elimination of nuclear weapons, including the signing of an international agreement for a total ban and the elimination of nuclear weapons. The convening of an international conference to reach this goal is also part of Hidankyo's basic demand.
The announcement that they were being awarded the Peace Prize was shared earlier today. It includes the statement that:
A nuclear war could destroy our civilisation.
Tanaka Toshiko and Ogawa Tadayoshi, both Hibakusha (survivors of the Hiroshima and Nagasaki bombings) spoke at the closing ceremony for EAG London this year, although I couldn't find any explicit link between themselves and Nihon Hidankyo.