Setsu Oiwa, wife of Kiyomasa Oiwa and relative of Anna Sasaki's foster mother Yoriko, resides with her husband in a rural seaside town between Kushiro and Nemuro in Hokkaido. This community faces economic decline after a bypass highway reduced visitor traffic. Their adult children live independently, with their daughter working as a Tokyo yoga instructor. Setsu maintains a consistently cheerful, nurturing, and easygoing nature. She warmly welcomes Anna into their home, settling her in their absent daughter’s room. Together with Kiyomasa, Setsu creates a supportive environment, encouraging Anna to explore locally while expressing concern for her safety and whereabouts. Perceptive of Anna’s emotional struggles, Setsu gently fosters social connections by introducing her to villagers like the Kadoyas and their daughter Nobuko. During Anna’s conflicts—such as a Tanabata festival argument with Nobuko—Setsu employs diplomacy, reassuring Anna that tensions resolve without blame. Her updates to Yoriko about Anna’s adjustment reveal attentiveness to Anna’s emotional state. Setsu involves Anna in daily tasks like harvesting garden tomatoes, using these moments to discuss family bonds and affirm Yoriko’s sincere care. She shares family photographs, including childhood images of Yoriko, helping Anna connect with her roots. Physically, Setsu presents a plump build contrasting with Kiyomasa’s slimmer frame. Throughout Anna’s stay, Setsu remains a stabilizing presence. She visibly delights in witnessing Anna’s gradual social integration and village connections. Her actions consistently blend practical care with emotional support, fostering the environment for Anna’s personal growth.