The Wakamaru robot, which went on sale in September 2005, is a domestic robot primarily intended to provide companionship to elderly and disabled people.

"One day I found him watching TV, which we never anticipated. Then sometimes he would start dancing. You never get bored because you never knew what he would do next," says Mr Ishihara.

And there are times when Wakamaru is irritating. Apart from the mistimed "how are you?" in the middle of a family row, Wakamaru is prone to not catching words first time around and ignoring instructions to "go to your recharge unit and be quiet" with all the obstinacy of a sulky child.