A Komainu (狛犬) or shishi (獅子) guardian lion statue at Hōkoku Shrine (豊國神社; Hōkoku-jinja) in Osaka Castle Park (大阪城公園; Osaka-Jō-Kōen), Osaka, Japan.
Komainu come in pairs of statues, usually almost identical, but one with its mouth open, the other with its mouth closed. This is a very common characteristic in religious statue pairs at both temples and shrines. In Asia the lion was popularly believed to have the power to repel evil, and for this reason it was habitually used to guard gates and doors.
Komainu strongly resemble Chinese guardian lions and in fact originate from Tang dynasty China. The Chinese guardian lions are believed to have been influenced by lion pelts and lion depictions introduced through trade from either the Middle East or India, countries where the lion existed and was a symbol of strength. During its transportation along the Silkroad, however, the symbol changed, acquiring a distinctive look.
Description adapted from Wikipedia article: http://en.wikipedia.org/wiki/Komainu