Masaki Aida is a male teenage student and a central character in the OVA Dark Future. He serves as the president of his school's newspaper club, a role that drives much of his involvement in the plot. Masaki has a notably casual and carefree outlook on life; he does not take many things seriously and often behaves in a mischievous or lecherous manner, such as trying to peek up girls' skirts despite frequently getting caught and punished for it. This playful and somewhat perverted nature contrasts with his responsibilities as a club leader.

Motivated by curiosity and a desire for interesting stories for the newspaper, Masaki teams up with fellow club members Kaede and Hinoki to investigate rumors of ghosts around the school. This investigation forms a key part of his role in the story, as it draws him and his friends into the darker events of the series. Masaki shares a close living arrangement with Shion, a classmate who becomes entangled with the psychic treatment club—a group that is revealed to be a front for a ring of rapists. His relationship with Shion is significant, as their shared home life connects him to the more sinister threads of the narrative, even though his primary focus remains on the newspaper club's activities.

In terms of development, Masaki begins as a lighthearted and somewhat irresponsible figure, but his involvement in the escalating dangers forces him into more serious situations. His notable abilities are primarily those of a typical student: he is resourceful in his role as a journalist and takes the lead in the ghost investigation, but he does not possess any supernatural powers or extraordinary combat skills. Instead, his character serves as an entry point into the mystery and a contrast to the more threatening elements of the story.