Toppings
So many things can be toppings. Some examples below.
Browned Negi
There are Japanese green onions called "negi" that are roughly 3 times the size of our green onions in all directions. I like to slice chunks of them and brown them in a pan, to use as a topping.
Corn
Toasted in a pan is good, with or without a little brown butter
Wood Ear Mushroom
Basically tasteless, but present for texture and/or protein
Wilted Spinach
Wilted, shocked cold, then excess water squeezed out by hand.
Shichimi Togarashi
Spicy powder to shake over the top.
Furikake
Traditional rice topping, with flakes of nori, sesame seeds, sugar, salt, msg, and other flavors.
Beansprouts
Blanched and shocked cold.
Preserved Bamboo shoots
I've never found them to use at home.
Green Onion
Chopped very fine
Sheet of Toasted Nori
As used to wrap sushi. Toasting stops it from going too wet, too quickly.
Kale
Sautéed with garlic
Mushrooms
More umami. Sautéed.
Slices of Steamed Fishcake
Buy a log from the asian grocery store.
Daikon Oroshi
Ground daikon radish