It's the sort of harsh sounding bass note at 0:20, like a sawtooth, that gets pitched down. It reappears around 0:25 and 0:30 and throughout the rest of the song. It must have some sort of pitch automation, but in a VST or Cubase I'm not quite sure where to start off.
I tried it in Korg's Polysix and Monopoly VST's, and Diva, but I couldn't get it to sound how I wanted. I'm wondering if it's some sort of envelope assigned to pitch, or maybe glide or something. Perhaps I can automate the midi pitch in Cubase but that sounds more difficult than playing the notes themselves.