expression, noun
dreamworld; dreamland; la-la land
Refers to an idealized, fantasy-like place or state of mind, often used figuratively for unrealistic or escapist thinking.
彼はいつも夢の国に住んでいるような人だ。
He's always like someone living in a dreamworld.
その計画は夢の国の話で、現実的ではない。
That plan is la-la land talk; it's not realistic.