Birthdays are acknowledged in Japan, but were not celebrated before WW2. The concept of celebrating the day you were born is totally foreign. Before, Japanese had only one ‘birthday’, which was the New Year’s Day, since everyone believed that they got older on that day.
Nowadays, Japanese mainly celebrate the children birthdays. Parents organise a more or less small gathering, a cake is customary and the number of candles depends on the age the birthday boy or girl is turning. The ‘Happy Birthday” song is sung in the dark and the candles have to be blown out. This part is similar to the west.
However, that does not mean, that adults do not jubilate over it at all. But it is customary that friends organise a party for the one who has a birthday, and all bills are covered by the guests, in order to let the person, whose birthday it is, to enjoy the day. This actually makes sense, doesn’t it? If everyone shares the cost for one it is not as “painful” as one person paying for everyone.
On the other hand, Japanese couples tend to reserve their actual birthday day for their partners. Generally they go on a date and spend the day together. Many Japanese women expect their partners to get them a special gift and will also buy their boyfriends or husbands one to show their love and affection. Gifts like accessories are popular since they can be worn practically every day and can remind them of their beloved ones.
Women in Japan also tend to have high expectations when it comes to their natal day. Since they will often reserve the whole day to celebrate it together with their partner, most will not complain or say anything if they end up doing nothing, but will be disappointed and are likely to dump their partner if such failure took place.
But do not worry, you do not need to go to the expense when celebrating your Japanese partner’s birthday. A card and a cake will be sufficient and if you add something small your partner’s birthday will be an unforgettable one. Do not forget to say ‘Otanjoubi Omedetou Gozaimasu!’ (Happy Birthday)