Thank you for the feedback and musical analysis!! :) I wanted something engaging yet mellow, so I tried to have a lot of movement in the tracks. The movement was to give that "bubbling up" effect too. I hadn't realized that there was distinct tonal ambiguity in "Nemutai", so that's a good catch on that. I will try to add more structure to the new soundtrack songs I do in the future. I had the same or similar notes to give the feel of a leitmotif.
I do too! I wish I composed more songs for the soundtrack, since I loved the theme for this one. I felt inspired by it. I originally planned on adding a folk song and a city pop song. I wrote out and translated lyrics, but I was running short on time.