This is the B Prize Diorama Figure of Tony Tony Chopper from the Ichiban Kuji Happy Birthday Chopper series.
The figure features Chopper holding a birthday cake with a cheerful expression, sitting on a snowy base inscribed with "HAPPY BIRTHDAY TONY TONY CHOPPER."
This limited-edition item was only available as a lottery prize in Japan 2010 and is a great addition for ONE PIECE collectors.