Sanae is the mother of Nagisa and wife of Akio. She looks a lot younger than her supposed age. Sanae is friendly with everyone, is strong-willed, and she always puts on a smile. She is quite popular among the townsfolk. Sanae teaches a small group of middle school students in a spare room of the Furukawa bakery.
Sanae co-owns the Furukawa bakery with Akio. She enjoys inventing new bread recipes which usually turns out to taste horrible. If Sanae hears or is told that her bread is horrible, usually from Akio, she will burst into tears and run around the neighborhood wailing. Akio will then stuff his mouth with Sanae's bread and chase after her claiming that he loves her bread. Akio reports that Sanae runs faster than he does.
Sanae can't hold her liquor and she becomes drunk after a single shot of whiskey.
Sanae was a middle school teacher but is later revealed to have high school level teaching knowledge. She and Akio used to be very busy and they couldn't spend much time at home but Sanae is usually the first to arrive home. Nagisa would wait outside the house for their return.
One day during Winter, Nagisa caught a cold waiting outside and both Sanae and Akio were late to return. Akio arrived home and discovered Nagisa buried under the snow. A doctor treated her but her condition didn't improve. Sanae and Akio deeply regretted their absence from Nagisa's life and decided to work closer to home to watch over her more closely.
Sanae is a close friend of Fuko's sister Kouko. Fuko tried and failed to keep her last name secret from Sanae but Sanae decided to not tell Kouko and to not ask why. Later after Sanae had forgotten Fuko, she acted as though she could see Fuko and was greatly saddened that Fuko had to disappear.
Sunohara Siblings' path
Sanae bumped into Tomoya and Youhei in town. Tomoya explained that Youhei wanted a girl to pose as his girlfriend while his sister Mei is visiting and Sanae agreed. Tomoya then tried to dissuade Sanae from following through with her initial decision but she remained unshaken. Youhei also fell in love with Sanae.
Later, Sanae revealed that she took pity for Youhei's situation and she had been trying to fix Youhei. After Mei returned home, Tomoya and Youhei wanted to see Sanae again and they discovered her husband Akio.
On April 16th, Nagisa invited Tomoya to her home. Sanae approached Tomoya and offered him a bread baked with a rice cookie at the core. Tomoya found it awful and Sanae ran away crying. That evening, Nagisa made dinner with Sanae and Tomoya had dinner with the Furukawa family. Tomoya enjoyed the atmosphere of the Furukawa family.
Sanae made the costume for Nagisa's drama.
Sanae was attending a neighborhood meeting when one of her former students, Tamura, visited the Furukawa bakery. Tamura explained that he had started a new school and he wanted to invite Sanae to teach in the new school. Akio doesn't want her to accept the offer because she attracts customers to the bakery. Sanae explained that the students under her tutelage will move to the new school.
Tomoya later revealed the story to Nagisa and she wanted to obtain opinions from Sanae's students. The students revealed that Sanae was constantly exhausted. A week later, Tomoya approached Sanae about her school. Sanae thanked Tomoya for his desire to help her and hugged him. They were witnessed by Yusuke. Yusuke gave Sanae a heart-warming speech about dedicating one's life to one's lover and Sanae revealed that she was Nagisa's mother. Yusuke was shocked and ran away.
The next day, Sanae surrendered her students to Tamura. Sanae cried as they left. Akio encouraged Sanae to express her true feelings. Sanae voiced her desire to continue teaching the kids and the kids agreed with her.
Sanae revealed to Tomoya and Nagisa that a friend of Akio had invited him to attend the opening of a new theatrical company. They encouraged Akio to attend it. Tomoya played baseball with the neighborhood kids and Sanae noted that Tomoya is very similar to Akio. 2 days after Akio's misadventure, Akio ran away from the hospital. Sanae begged Akio to not run around and make her worry and Akio promised to stay by Sanae's side.
Sanae requested help from Yagi, a midwife and an old classmate, to help with Nagisa's pregnancy. In the middle of Summer, Nagisa came down with fever and Tomoya requested Sanae to tend to Nagisa while he was at work. Sanae explained that Nagisa may have to undergo an abortion if Nagisa's fever doesn't subside because she may not survive the childbirth.
Sanae took Ushio under her care while Tomoya was mired in depression. She was strict with Ushio because she wanted Ushio to appreciate her father's love. 5 years later, Sanae planned for Tomoya to meet his grandmother Shino. Tomoya then thanked Sanae for taking care of Ushio for 5 years and requested to reclaim Ushio from Sanae's care.