Melt butter in a medium saucepan. Add the shrimp heads and shells and saute until they turn orange. Sprinkle in sugar and cook for another minute. Pour in water and bring to a boil and then lower the heat to gently simmer for the next 30 minutes. Strain the stock and discard the solids. Put the stock back in the saucepan and bring to a gentle simmer. Add in mashed sea urchin roe. Use an immersion blender to make the broth smooth if you have one. If you don't have one, you can always blend it in the blender. Have a taste and season with salt to your taste. The broth should have that familiar taste of sea urchin, savory, umami, and slightly sweet
Assembling:
While the broth is cooking, cook the instant noodle according to the instruction on the package. Do not overcook the noodle. Rinse with cold water. Portion out noodles into serving bowls. Top with few slices of the remaining sea urchin on top of the noodle, sprinkle with green onion slices
Ladle the sea urchin broth in another bowl and serve immediately with the noodles. Use a chopstick to pick up some ramen into the sea urchin broth bowl and dip the noodle several times and then slurp it in. That's how you eat it ;)