However, I did spot this display at my local market down the street from my house. The hiragana reads hiiragi (ひいらぎ) or holly in English. According to the Wikipedia entry, sardine heads and holly leaves are placed on entrances to Japanese homes to keep bad spirits from enter.
Nikon D600 with Nikon 85mm f/1.4 AI-S @ f5.6, ISO 100, 1/100 sec.