Japan's SoftBank on Thursday unveiled what it billed as an "emotional" humanoid robot that will entertain customers at the mobile carrier's phone outlets -- and maybe become a member of their family.

Company president Masayoshi Son joked around with the talking, dancing and singing humanoid named Pepper at an event just outside Tokyo.

The bug-eyed 120-centimetre (3.9-feet) tall robot may eventually take on a customer-service agent role at Softbank's stores, Son said, adding that its "human emotions" made it a perfect fit for families in a rapidly ageing society where labour shortages loom.

"Pepper is not yet perfect, but he can already understand about 70 to 80 percent of spontaneous conversations," Son told reporters.

The robot can learn and "understand" human facial expressions and emotions, making it a perfect party companion, babysitter or even caretaker for seniors, said the flamboyant chief executive, who led SoftBank's $22 billion purchase of US-based Sprint last year.

"Pepper could become a very good friend and a powerful tutor for a child, for example. He could learn about a family over several years... and actually become a member of the family."

Robots are common in technology-obsessed Japan. A humanoid developed by automaker Honda chatted and kicked around a soccer ball with visiting US President Barack Obama earlier this year.

SoftBank's Pepper, which would be sold from February for about $2,000, was developed by French robot maker Aldebaran Robotics and would be manufactured by Taiwan's Foxconn, a major supplier to Apple.

It will start greeting customers at two Tokyo outlets from Friday, Son said.

SoftBank is well known in Japan for its quirky TV commercials in which a snow-white dog heads a multicultural family.