Tamaki Iwato, born in July 1983, is the younger sister of Tsubame Iwato, who perished in the 2011 Great East Japan Earthquake. Following her sister's death, Tamaki became guardian to her orphaned niece, Suzume Iwato, raising her in Tonami. She works at the Tonami Fishing Port within a fishery cooperative, alongside her colleague Minoru Okabe.

Tamaki devoted twelve years to raising Suzume as her own daughter, providing stability after the earthquake. This guardianship defines a core aspect of her life. When Suzume unexpectedly journeys across Japan, Tamaki pursues her, driven by deep concern. During a confrontation heightened by supernatural forces, specifically Tamaki's temporary possession by the keystone guardian Sadaijin, she voices long-suppressed frustration and resentment about the personal sacrifices made while raising Suzume. She explicitly calls Suzume a burden and declares, "you are not my daughter." Tamaki immediately feels profound remorse and regret upon seeing the emotional pain her words cause.

After the possession ends, Tamaki accompanies Suzume and others traveling towards Tohoku. They reconcile during this journey; Tamaki affirms the deep meaning of their relationship despite the conflict. She acknowledges the sacrifices her role required but states they were ultimately worthwhile.

In her personal life, Tamaki works closely with Minoru Okabe, who harbors romantic feelings for her. Tamaki appears unaware of his interest and expresses personal insecurities about marriage prospects, citing her status as a single mother raising a child as a potential hindrance. Following the resolution of supernatural events involving the Worm and the Ever-After, Tamaki returns to Kyushu with Suzume.