The Japanese say future whaling would be sustainable and would have safeguards including set quotas and independent observers.
The move follows defeats on two key motions for the Japanese delegation on day one.
But the arrival of delegates from Togo and Cameroon could tip the balance in Japan's favour.
Australian Environment Minister Ian Campbell said Japan's whale hunts were "inhumane and disgusting".
Unveiling a report by the pressure group International Fund for Animal Welfare, he said Japan's argument that it conducts whale hunts humanely was "absolutely false".
Japan says it will consider leaving the IWC if it does not agree to an eventual resumption of commercial whaling.