Tororo is grated yama imo, a type of mountain yam in Japan. Tororo has an extremely gooey texture and is commonly added to side dishes or eaten with rice or noodles. It's extremely nutritious and has high amounts of vitamin B1, vitamin C and potassium. Tororo is also more popular with tourists than natto (below) because it has a subtle taste and smell.
Okra is a flowering plant that's grown in tropical, subtropical and warm temperate regions around the world. It has a subtle taste and a slimy texture when mixed well. Okra is very rich in vitamins, especially vitamin C and K, and contains moderate amounts of thiamin, folate and magnesium. It's often added to salads or noodles in Japan.
Natto is made of fermented soy beans and is commonly eaten with rice in the Kanto region. Despite being a great source of vitamin K, vitamin C, manganese, iron and dietary fiber, it remains unpopular outside of Japan due to its slimy texture, pungent odor and unique taste. It's definitely considered an acquired taste and even locals have trouble swallowing it. But many agree that the health benefits outweigh the smell and taste. And, natto can even improve your skin!