Prepare the chashu pork: Roll the pork belly tightly and tie with kitchen twine. Sear all sides in a hot pan until browned.

Make the chashu marinade: Combine soy sauce, mirin, sake, sugar, garlic, and ginger in a pot. Add the seared pork and enough water to cover. Simmer for 1.5 hours.

Prepare ramen eggs: Soft boil eggs for 6-7 minutes, then cool in ice water. Peel and marinate in leftover chashu broth for at least 1 hour.

Make the broth: Combine chicken and pork broth in a pot. Add soy sauce, sesame oil, and season to taste. Simmer for 30 minutes.

Prepare toppings: Slice chashu pork, halve marinated eggs, blanch bean sprouts, and chop green onions.

Cook noodles: Boil ramen noodles according to package instructions (usually 1-2 minutes). Drain and rinse under cold water.

Assemble ramen: Place noodles in bowls, pour hot broth over them. Arrange chashu slices, eggs, bean sprouts, bamboo shoots, nori, and green onions on top.