Clean the octopus thoroughly and cut it into bite-sized pieces.
Prepare radish, green onions, garlic, and water dropwort.
Pour water into a pot, add radish and garlic, and bring to a boil.
Once the broth develops flavor, add the cleaned clams and cut octopus.
Add green onions and water dropwort, and season with salt and pepper.
Serve hot immediately once all ingredients are fully cooked.