Apparently it’s a choking thing.

Six people have choked to death and five others are in a serious condition after eating traditional glutinous "mochi" rice cakes to celebrate the New Year in Tokyo.

The victims, in their 70s or older, died of suffocation over the weekend after eating the New Year delicacy, fire department officials said today.

During the New Year period, one of Japan’s biggest holidays, families traditionally cook "ozouni" soup and put the sticky rice cakes in the vegetable broth.

"Please be aware that mochi, which is so sticky, may cause suffocation if you swallow mochi without chewing it well," the fire department said.

It is advising people, especially the elderly and infants – several of whom die each year from choking on mochi – to cut it into small pieces before eating it.