SAN-KEN The Three Sages

I'm a huge fan of Kevin's works and this song is by far my favorite of the season 2 OST, but I've constantly had questions about it. I'm a huge music nerd so this question really nags at me whenever I listen to the song. I can't tell it's time signature and rhythm at all. The song's opening has a consistent 8th notes run, which sounds like the song is ~120 bpm but when the melody first appears, the notes seem almost off beat. This question gave me a few possibilities but none of them seem to work. My first thought was that the song could be in 12/8 and what we here are quarter notes as opposed to dotted quarter notes, explaining that off beat sound. However, this is impossible as the 8th notes runs can be easily divided into a 4/4 measure, having it be 12/8 would screw up the phrasing. This was the same problem with my second idea, that being that the song is in 3/4, but I ruled this out very fast as not only does the phrasing fr the 8th notes not work, but it completely screws up the melody's phrasing. My final thought was that the tempo was actually lower that 120 bpm and the quarter notes synced up with the beats and the 8th notes were actually 16th notes. That theory has seemed really close to the right answer but even with that, the notes sounding off beat still remains. That's where I ask you guys, what kind of rhythm stuff do you think Kevin did to pull off that sound? Your answers are really appreciated.