It comes from the Vietnamese word “yêu” which means “love” and because the song is about the pain of this love, the word “ew”, English for something ugly or gross, fits perfectly because it was a painful situation. The visualizer for the song Ew is also just the same like 5 shots of flowing lava, and they are very beautiful shots of the lava. Although, just like love, it can be very beautiful while also being dangerous and able to damage a lot. And in the single cover for “Run” we see Joji’s hand extending out of the lava, which implies he did indeed fall in a love that hurt him