Twelve at first seems to see Lisa as a play thing. However it becomes clear that he begins to develop a strong amount of feelings for her, this shown when she runs away from her house and he chooses to find her and bring her to the hideout in which him and Nine are. He is very empathetic towards her and cares for her deeply as when she was trapped in the airplane with a bomb that Five had set up he was set on saving her, even with Nine's initial disagreement with such. After that Lisa runs away, thinking she is simply a burden in which he immediately goes off to find her as Five sends Sphinx a message on how she is held captive in the ferris wheel. All the while trying to disarm the various bombs attached to her body he comforts Lisa, telling her nothing is her fault, even when he betrays Nine on the atomic bomb's location as to save both Lisa and himself. After, the two go to an amusement park together Lisa is worried about Nine in which Twelve then sets off to save him, however later is found by Lisa who takes care of him as he falls unconscious, then later hugs him whilst crying when he regains consciousness, glad to see he is alive. The two together watch the sky as the atomic bomb will go off at any given moment, Twelve sharing on how he and Nine have always been alone and thought they needed nobody, however he was glad he had met Lisa, making her smile and cry as they reach out to hold each others hands when the atomic bomb detonates in the stratosphere. It seems they care deeply to each other, even to the point of possible romantic feelings.
Nine dislikes Lisa and considers her weak and a burden most of the time, but is shown to develop a friendly relationship with her by the last episode. Lisa asks Nine in the final episode what kind of music he's always listening to and he tells her it's music from a cold land, meaning Iceland. He also tells her that in Iceland, VON means "hope." Lisa seems to still be mourning over Nine and Twelve a year after their death.
Lisa's mother is very protective and obsessive over her. She is very scared that Lisa will also one day leave her just like Lisa's father did once. She is also shown to be mentally unstable and slightly obsessive because of sending multiple text messages and shaking Lisa when she is talking to her. Lisa runs away from her in episode 3 and does not see her again, but there might be a chance of her returning back home with her mother since she has nowhere to live after Twelve and Nine's death in the last episode.