The Sunshine City aquarium atop a high-rise building in downtown Tokyo has a new star in four-month-old river otter Haku. Greeting visitors either on a leash or from a bag, the 3 lb "Haku", whose name itself means white, is distinctly white even at her current age. While river otters are born with white fur, by the time they've reached Haku's age nearly all have turned into the normal black. For visitors, Haku's appeal is instant as handlers walk her around the park. Others said the chance to see a river otter, and especially a rarer white otter up so close, was a rare opportunity. The aquarium has seven river otters, including Haku, and while she isn't yet old enough to be put on display normally with the rest of the adult otters, she's busy entertaining visitors on her daily walks.