It was sometime in the 1950s when the Japanese culture began to embrace Western culture and celebrate the individual birthday of someone. Before this, all Japanese birthdays were observed over the New Year.
• If you want to speak happy birthday in Japanese, you will typically say “otanjoubi omedetou gozaimasu.”
• If the individual is near to you, you will disregard the o and the gozaimasu, which are considered more formal and proper, and say “tanjoubi omedetou.”
• You should add an expression of gratitude as a form of respect for authority figures.
• Add a name to make it personal.
• For your spouse or your partner, say “Aisuru anatani otanjo biomedetou,” which means happy birthday, my love.