Matsuyuki admitted his love to her on the day that she died; however, she didn’t return his confession in favor of chasing after Jinta. It is hinted that she has feelings for Jinta, and only Jinta is able to see her. This is confirmed when Menma wrote a letter for Jinta, which read, “I love you, Jin-tan. It’s the “I want to marry you!” type of “I love you.””
Menma is able to reveal her presence to her friends by carrying objects, flickering the lights, etcetera. She is also able to communicate with them by writing in her diary. She seems to think that her wish was to send a rocket to Heaven with a note to Jinta’s mother, so the reunited Super Peace Busters attempt to create one. Menma also wishes to be reincarnated after passing on so she can be in the world again, back with her friends.
Without her, Menma’s family is falling apart. Her mother is unable to move on from her death. Her father, who is hinted at being abusive, wants their family to overcome the grief. He does this by hiding all of Menma’s possessions, yet it does her mother very little good. Her younger brother barely remembers her but wishes that their family could move on. He feels neglected by his mother since she is still stuck on Menma.