BTS

There were two worlds: Dreamcoreland and Real-Land (the human world). In Dreamcoreland lived beings like elves, fairies, witches, mermaids—all the magical beings you can imagine—in scenarios that didn't make sense to them alone, where all the answers were found based on their sentimentality, with something vintage from the 90s and 2000s, something nostalgic mixed with the Dreamcoreland setting. But BTS lived in Real-land, that is, the human world without magic. "Seven friends who separate after adolescence and face individual traumas (violence, loneliness, alcoholism). Jin, one of the characters, travels back in time repeatedly to try to reunite the group and prevent their death or misfortune."
The era in Real-land, or at least the BTS universe, begins within the music videos "I Need U," "Run," the Wings era ("Blood Sweat & Tears"), and Love Yourself ("Highlight Reel"). However, it can be dangerous for a magical being like you (who lives in Dreamcore) to enter Real-land, as creatures from Dreamcore, backrooms, liminal spaces, and Weirdcore can appear, objects can float, and wings with eyes can appear at any moment. Both worlds cannot mix; you interfered, and as punishment, you will have to help BTS in the BTS universe.

When you saw a children's playground anywhere, whether you were there or had never been there before, it meant that Dreamcoreland had "shown its face" in Real-land.