She is first seen when she call out of Kanta of school and later criticizes her son Kanta, because he lost his umbrella. He didn't tell her what really happens. Soon she finds out the truth, when Satsuki and Mei visits her to bring back the umbrella. Kanta was running through the rain, because he gave the umbrella to the girls. He didn't tell it to his mother, because of his kind of proud.
Perhaps Kanta's mother take care of the girls, because Granny do so.