Nana Shimura/Relationships

Kotaro Shimura
Despite the little seen, Nana loved her son Shimura very much and cared for him. However, after her husband was murdered, Nana did not want her son to have the same fate, so, much to her dismay, she moves away his son from the world of heroes, left him in the care of a foster family.

Nana even asked Gran Torino and Toshinori to, under any circumstances, never come into contact with Shimura, preventing her close friends and allies from searching for him before her own death.

Sorahiko
Gran Torino and Nana Shimura were close allies and friends. She trusted him enough to tell him about the One For All, as well as to entrust him with the training of who would be his successor: Toshinori Yagi. When the three tried to face All For One, Nana sacrificed her live to allow them to escape, entrusting the safety of Toshinori to him.

Sorahiko became a teacher in U.A. in order to train Toshinori solely because of the promise he had made to her.

Toshinori Yagi
Nana Shimura was All Might's mentor and his predecessor, the 7th inheritor of the One For All Quirk. Nana was the one that told All Might that a true hero should smile no matter what, to reassure the people and to not only protect their lives but also their hearts. All Might greatly respected her as a mentor, friend and hero; to the point that he comes to consider her as his own mother.

All Might became enraged when All For One badmouthed her and was distraught when it was revealed that Tomura is Nana's grandson.

He still mourns her death even years on and after learning that Tomura Shigaraki is her grandchild, he vowed to find him and save him.

All For One
As one of the inheritor of One For All, Nana was destined to fight against All For One. She considered him a cruel and manipulative person, who scoffing irrationally at the people that just want to live their lives. Along with Gran Torino and All Might, she tried to stop him, but was killed by All For One in battle while let All Might and Gran Torino to escape.

For All For One, Nana was a pitiful woman. He mocks her commitment to ideals and disparages her strength and, by his admission, declared the latter died a pitiful death. All For One tarnished her memory by knowingly taking in and grooming her grandson Tomura Shigaraki to be a Villain and his successor.