The story reminds me a lot of liminal spaces. The atmosphere really fits that, and C418 is a great choice of inspiration :3 I'm a big fan of the synth for the 'Watching Bubbles Float', I think you do a great job with picking sounds. And I wouldn't have noticed the motif as a leitmotif if you hadn't pointed it out, but actually I found it a cool effect to look for it and have it be slowed down compared to 'friendly fish factory' track (which I adore)