Nana Shimura/Relationships

Kotaro Shimura
Despite the little seen, Nana loved her son Kotaro 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 sent her son away from the world of heroes, leaving him in the care of a foster family.

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

Unfortunately for Nana, her actions would ultimately cause her son to resent and detest her legacy for the rest of his life. Kotaro would consider his own mother as a demon, believing she put up her own son for adoption due to putting her duties as a hero before her family. While he would later go on to have a family of his own, he was abusive towards his son, Tenko, and frequently abused him whenever he talked about heroes or her in general. The abuse ultimately drove Tenko to murder his father and his whole family, thereby making Nana indirectly responsible for Tenko becoming Tomura Shigaraki.

Sorahiko Torino
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 her successor: Toshinori Yagi. When the three tried to fight All For One, Nana sacrificed her life 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 who 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 began 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 now and after learning that Tomura Shigaraki is her grandson, becomes devastated and first wants to track Tomura down, though Gran Torino convinces him that he's still a villain and needs to be treated as such.

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 who 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 letting All Might and Gran Torino 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.