Stage Sekai (ステージのセカイ) is MORE MORE JUMP!'s
sekai.
It is accessible via the song "Idol Shineitai".
Minori, Haruka, Airi, Shiho, Miku, Rin, Len, Luka, MEIKO and KAITO have conversations here. Additionally, area items that increase the power of MORE MORE JUMP! and VIRTUAL SINGER cards can be found here.