Called "Smart-han", it's a hard plastic tube that allows people to pack in rice and various fillings for an onigiri that screws out like a push-pop.
There's a trailer for the Smart-han, which is mostly tongue in cheek (ditto for the above image). This is part of Takara Tomy's "interesting bento series"—it's more to amuse people than revolutionize the way onigiri are made.
Smart-han is going on sale in Japan later this month for ¥840 (US$10.70). There's a blue version for men and an orange version for women. Oh! Rice one!
Smart-han [Official Site]