Boil water in a pot. Add Chinese noodles and chicken breast. Cook chicken for about 2 minutes until done, then remove and let cool. Cook noodles as per package instructions, rinse under cold water, and drain.

Shred the chicken breast into bite-sized pieces.

Trim the roots off the kaiware sprouts. Slice the myoga thinly. Remove the seed from the umeboshi and mash it.

In a bowl, mix the shredded chicken, kaiware sprouts, myoga, mashed umeboshi, and sesame oil.

In another bowl, mix sugar, salt, vinegar, soy sauce, and water to make the cold noodle sauce.