The following metanode contains Japanese food items that would generally not be considered "food" in the West.

• basashi (raw horse meat)
• deep-fried shrimp heads
• hormonyaki (sautéed tripe)
• ikizukuri (live fish)
• kimosui (eel liver soup)
• kinkan (grilled chicken ovaries)
• kotsu mushi (steamed fish heads)
• nankotsu (chicken breast cartilage)
• natto (fermented soybeans)
• sashimi (raw fish or meat)
• shiokara (rotten squid brain puree with tentacle bits)
• shirako (fish sperm)

(And you thought tofu was weird.) Somewhat less traditional, but no less Japanese, are the following bastardized versions of Western foods:

• Japanese pizza
• spaghetti omelette

Feel free to /msg me any additions. See Japanese Food for a listing of less unusual stuff (only natto is duplicated here).