Add the chicken thighs, chicken broth, dried shiitake mushrooms, ginger coins, smashed garlic, scallion whites, soy sauce, mirin, and kombu to a 6-quart slow cooker. Stir gently to combine. Do not add the miso paste or sesame oil yet.
Cover and cook on LOW for 8 hours or HIGH for 4 hours, until the chicken is fall-apart tender. Keep the lid on for the entire cook time.
Transfer the chicken thighs to a plate. Discard the skin and bones and shred the meat with two forks. Remove and discard the ginger, garlic, kombu, and scallion whites. Remove the rehydrated shiitakes, slice them thin, and reserve for topping.
Ladle 1 cup of hot broth into a small bowl and whisk in the miso paste until completely smooth. Stir the mixture back into the slow cooker, then stir in the toasted sesame oil. Taste and adjust with additional soy sauce or a splash of rice vinegar.
While the broth finishes, bring a small saucepan of water to a rolling boil. Lower in the eggs and boil for 6 minutes 30 seconds, then transfer to an ice bath for 5 minutes. Peel and halve.
Cook the ramen noodles in a separate pot of boiling water according to package directions. Drain well. Do not cook the noodles in the slow cooker.
Divide the noodles among 4 deep bowls. Ladle the hot broth over the noodles, then top with shredded chicken, halved eggs, sliced shiitakes, scallion greens, corn, nori strips, and chili crisp. Serve immediately.