Peel daikon and cut into 1 inch rounds.
Combine the chicken, sherry or sake, mirin, soy sauce, sugar, and water in a medium saucepan. Bring to a boil, then reduce to a simmer and add the daikon.
Add enough water to completely cover the daikon and chicken. Cover and simmer 45 minutes to an hour, until the daikon is brown and tender and the chicken is falling off the bone.
Spoon chicken and daikon into serving bowls with some of the broth. Top with green onions and sesame seeds. Serve immediately.