Christmas in Japan is more of a day for couples.

Literal

Japan [possessive-の] Christmas [topic-は], if-anything lovers [possessive-の] day [copula-です].

どちらかというと 'if anything, more like' hedges the classification. 恋人たちの日 'lovers' day' — in Japan, Christmas is primarily a romantic holiday (like Valentine's Day in the West) rather than a family one. A useful cultural note for learners.