Izumi/Relationships

Mizuha's grandfather
Izumi and her father have a very rocky relationship. While Izumi was trying to convince her father to leave the Guardians, which had devolved into a cult rather than a defense force at this point, her father tried to do the exact opposite: to get Izumi involved. After her mother died, he tried to set Izumi up with a high-ranking member of the Guardians, to which she reacted with shock and ran away.

While her father has a much milder temper now, Izumi doesn't trust him and won't let Mizuha near him.

Mizuha
Izumi's love for her daughter soon turned into an obsession as she wanted her to become perfect in every way. While this didn't take a toll on Mizuha's emotional state in her early childhood, she grew up believing she was nothing but a trophy to her mother. Eventually, this led her to develop a grudge against her and killing her.

Mizuha's father
Before she knew about his affiliation with the Guardians, Izumi seems to have loved her husband very much. After she found out, they fought a lot more and chances are that the only reason Izumi hasn't divorced him yet is Mizuha.