It's a prizon break unlike any other: a young Humboldt penguin known only as "Penguin Number 337" escaped a Tokyo aquarium in a brazen escape.
The one-year-old Humboldt penguin scaled a rock wall and squeezed through a fence during a daring bid for freedom some time in the past week, sparking a penguin hunt that included a city-wide call for information on the tubby fugitive.
Tokyo Sea Life Park, on the shores of Tokyo Bay, was alerted to the escape of the bird, known only by its number, after receiving a photograph on Sunday that supposedly showed it swimming in the bay.
Kazuhiro Sakamoto, the park's deputy director, thinks it may have been a case of happy feet.
"The penguin hatched last year on January 27, so it is still a very young penguin," Sakamoto said.
"We think that because of its young age, it might have escaped due to its curiosity and yearning for adventure."