オネガイセカイ (Onegai Sekai)

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Just one word is fine.

The song is featured in Hitoshizuku-P × Yama△'s albums After the partY and Mistletoe ~Kamigami no Yadorigi~ (ミスルトウ～神々の宿り木～), and BinaryMixx's compilation album V Love 25 -Gloria-. It has entered the Hall of Fame.