I'm assuming that Jenny Ji hasn't hoodwinked us by covertly consulting the score, before reviewing this song in this Youtube video. To improve my ear training, I deliberately refrained from reading the score too. But every "Seventh", that Ji identifies, sounds like the tonic scale degree to me! I just don't hear any Major or Minor Sevenths. Do these Sevenths sound like the tonic to anyone else? What's wrong with my hearing?
At 10:57, Jenny Ji says
Sev, one, five, three. Sev, five, three. Seven.
At 11:38, Ji remarks
This song is, like, exploiting how the major seventh chord on one utilizes, like, both tonic and dominant functions.
It's kinda cool, cuz if you just play within the major seventh chord, and add in like a nine, you get like scale degrees 1, 2, 3, 5 and 7. And then you can build dominant and tonic. So it can be dominant and tonic!
Jenny Yunyi Ji graduated with "the Bachelor of Music program at the Eastman School of Music and is currently pursuing a Master's in Piano Performance under the studio of Jon Nakamatsu at the San Francisco Conservatory of Music."
In 2017, according to Linkedin.