It's not that Japanese people are Christian — they're not. Only %1 of people in Japan are Christian. It's because people think Christmas is cute.
In Japan, Christmas isn't a family thing. It's a romantic night for couples. Date places — restaurants, attractions and love hotels are busy on Christmas.
Many young couples buy each other a small Christmas gift.
In Japan, Christmas is a work day. It's also a big drinking night — it's a day that Japanese singles tend to feel a little lonely. Clubs are packed.
Christmas is such a romantic concept in Japan — that it's a popular theme for love hotels. Such hotels keep their Christmas decorations up all year round.