land of everlasting summer
A poetic or figurative expression for a tropical or subtropical country where it feels like summer all year round.
ハワイは常夏の国として知られている。
Hawaii is known as a land of everlasting summer.
Compound of 常夏 (everlasting summer) + の (possessive particle) + 国 (country). The exact origin is uncertain, but it is a natural descriptive phrase.