Miu stood as Nikuko's closest friend before Kikuko's birth, a time when Nikuko went by another name. Their bond formed while working together at a club establishment. Miu stepped in to help Nikuko repay significant debts incurred by one of Nikuko's ex-partners, providing crucial financial assistance during Nikuko's earlier adulthood.

After the death of Nikuko's biological family members, Miu and Nikuko forged a sister-like bond. Miu became an anchor, helping Nikuko rebuild a sense of family connection during that difficult period. This relationship represents a vital support system in Nikuko's past, preceding her life in the fishing port town with Kikuko.