Kumi usually understands her husband's tsundere modes especially when it comes to Kusuo but when Kumagoro goes excessive actions towards his hate on Kuniharu, she'd join the others on contemplating him. She still loves him after that as she is the only who understands him, aside from their daughter.
Mikoto got close with Kusuo's grandmother, Kumi when the two met in a mall. Before then, Kumi was being criticized for wearing a teenage clothes, which is really not suitable for her. Mikoto however, being a gyaru love those type of clothes that Kumi wears and the two started to talk like they were friends. The meeting of the two worried Kusuo but he later stopped following the two because it was too unbearable. Mikoto then started calling Kumi 'grandmother' and Kumi casts her vote for Mikoto as her granddaughter-in-law.