Apollo in Tune In to the Midnight Heart is the mysterious late‑night radio (and stream) host whose voice once kept the protagonist Arisu company when he was lonely, but whose real identity is hidden behind that on‑air alias.

Who Apollo Is (In-Story)

  • Apollo is a girl who hosted the program Midnight Heart Tune (or similar late‑night broadcast) that Arisu listened to alone at night.
  • She suddenly stopped broadcasting one day without explanation, which deeply affected Arisu and became the emotional starting point of the story.
  • Years later, Arisu transfers schools specifically to track down the real person behind the name “Apollo,” knowing only her voice and on‑air persona.
  • Clues point to Apollo being one of the four girls in the high‑school broadcasting club, but the manga deliberately keeps which girl it is a mystery and central hook.

In other words, Apollo is:

  • The anonymous comfort voice who helped Arisu through lonely nights
  • A hidden member of the broadcasting club
  • The main mystery Arisu is trying to solve throughout the series

How the Story Frames Apollo

  • Arisu describes Apollo’s voice as his only solace at the end of harsh, lonely days, almost like a lifeline.
  • He knows nothing concrete about her—no real name, no face—only her voice and the pseudonym “Apollo,” which turns her into a kind of distant “radio angel” in his memory.
  • The plot revolves around Arisu promising to help each broadcasting‑club girl pursue a voice‑related dream, both to repay what Apollo did for him and to uncover which of them is actually Apollo.

Do We Know Her True Identity Yet?

Public information and fan discussions agree on a few points:

  • The work itself presents Apollo as “most likely one of the four members in the Broadcasting Club,” but does not plainly confirm which girl she is in basic plot summaries and character pages.
  • Fan theories (videos, Reddit threads, etc.) argue over which heroine fits best based on voice, behavior, and key scenes like Apollo’s confession, but these are speculation , not official confirmation.

So, answering your question as simply as possible:

Apollo is the anonymous late‑night radio host whose broadcasts once saved Arisu from loneliness, now believed to be one of the four girls in his school’s broadcasting club, but her exact identity is intentionally left as the series’ central mystery.

Information gathered from public forums or data available on the internet and portrayed here.