"Antenna" recounts the disintegration of a family following the disappearance of six-year-old Marie. It is narrated fifteen years later through the first-person perspective of Marie's elder brother Yuichiro, now twenty-three and studying philosophy at university in Tokyo. Yuichiro, his brother Yuya, and their mother, are all locked in a cycle of grief, each seeking solace in different ways: the mother is immersed in a religious cult, Yuya is recovering from a nervous breakdown, and Yuichiro suffers from recurring nightmares from which he gains relief through self-harming.

Yuichiro's one close friend, a fellow student called Miki, gives him the contact details for Naomi, an SM queen. Around the same time, a TV director named Soma persuades him to undergo regressive hypnotherapy in order to try to uncover any repressed memories that may yield clues to the past.

Yuichiro experiences a kind of awakening as Naomi forces him to live out a sexual fantasy that enables him to connect to his own feelings and to the people in his life. As events take on an increasingly unreal tinge, Miki becomes alarmed and tries to stop him from attempting to heal himself through Naomi and Soma. Yet Miki is there whenever he needs her, his guardian angel of sorts.

Yuichiro descends into an increasingly erotic dreamlike world until he collapses into unconsciousness. In a climactic near-death experience, he exorcises the ghost of his sister, putting her soul to rest and thereby frees his family from the cycle of grief.