: Victims experience a "new instinct"—specifically a supernatural physical change that drives them to target their close friends.

This looks like a track from the series (often associated with the Pururun or Punyu Puri soundtracks from Japanese rhythm games, pop’n music , or similar BEMANI titles). The “ff” indicates fortissimo (very loud), and “Ti” likely refers to the note or a vocalization.

As they moved through PunyuPuri’s strange cadences, an echo came—not from buildings but from footsteps. A boy, perhaps twelve, barefoot on cold concrete, had stopped to watch. He kept his distance, but the music reached him like a letter. An elderly woman crossed the bridge, still in her robe, hands in her coat pockets, and smiled with a face that had room for many songs. Sound, they found, delivered company.

While the game can be played on various peripherals, most competitive players recommend: Mechanical Keyboard:

The emotional impact of "Rondo Duo" on listeners would be profound, given its likely narrative of dramatic awakening or realization. The rondo form provides a sense of familiarity and structure, while the fortissimo at dawn introduces an element of suddenness or epiphany.

Given the disparate elements, "Rondo Duo -Fortissimo at Dawn- PunyuPuri ff -Ti..." could belong to one of three genres: