I couldn’t find any arrangement of the gorgeous leitmotif featured in "Forest of the Abyss" and "The Former Child of Ido Front", no matter how long I searched.
So... I transcribed it myself.
For the piano version, I gravitated toward the melancholic atmosphere and harmonic richness of "The Former Child of Ido Front", so I focused on that. Still, I highly recommend listening to both original tracks—they’re both beautiful in their own right. ("Forest of the Abyss", in particular, features a hauntingly beautiful cello solo that stands out as a highlight.)
"Forest of the Abyss" is used in many key scenes: when Ozen leads Reg and Riko along the staircase to her quarters, testing their resolve; later on, when Reg must help Riko after she’s poisoned by the Orbed-Piercer; and finally, during the infamous elevator scene. It’s a track filled with melancholy and remorse—simple on the surface, yet emotionally intense and thought-provoking.
"The Former Child of Ido Front", on the other hand, plays during "Dawn of the Deep Soul", when Nanachi wanders the Ido Front base at night, remembering Mitty. The “former child” in the title could clearly refer to either Mitty or Nanachi. This piece is also steeped in melancholy, but with an even stronger sense of regret—of what could have been.
The original track features ambient pads, choir, and eventually high piano notes played in a very rubato, expressive style.
On the piano, I interpreted the sustained tones of the choir and pads with generous use of the damper pedal, while mimicking the choir’s build-up through arpeggiated chords.
The arrangement turned out deceptively simple: it stays in the original key signature of B♭ minor, which means five flats, and moreover it has plenty of dense chords. Add to that a very expressive, rubato tempo, with a very soft dynamic, and you’ll need a delicate touch and a lot of emotional nuance to really bring it to life.
