Filmed in one take in the back of a moving van in a sing-a-long style, the five women of Red Velvet delivered a rendition of their Hitchhiker-produced song while the songwriter, clad in his regular aluminum attire, drives. Aside from some color alteration and animated effects, the music video is extremely minimal, and its vertical orientation suggests it was filmed on a cell phone.
A vocally-dominant song, "I Just" showcases the girl group's individual color tones through the verses, especially Wendy who is given a chance to explore her vocal range. All five unite for the harmony-heavy chorus. This brand of vibrant future bass made for one of Red Velvet's most exciting b-sides, with the beat building up to an explosive, chanting electro-pop hook before dropping to soft synths until its inevitable build to the energetic chorus once again.
“I Just” was originally released on Red Velvet’s Perfect Velvet album in November. At the time, Wendy told Billboard that the album, “can show the perfect Red Velvet performances and songs.”
Upon its release Perfect Velvet became the girl group's fourth album to top the World Albums chart, making Red Velvet one of only four K-pop groups, and the only female act, to see so many albums top that chart. Since then, the quintet released an extended version of the album called The Perfect Red Velvet, led by the single "Bad Boy."