Happy Birthday in Japanese: お誕生日おめでとうございます (Otanjoubi Omedetou Gozaimasu)
“Congratulations on your birthday!” In Japan, they celebrate Shichi-Go-San, which literally means 7-5-3. These are lucky numbers and children go to a Shinto shrine on 15th November if they had a lucky birthday that year. They pray and give thanks for their good health and strength. All children go when they are three years old, boys when they are five, and girls when they are seven.
(Via Fluent in 3 months – Language Hacking and Travel Tips)
Odds are good that I will get to say this to my son in Japan later this year when he comes to visit. The trip is my present to him (and me ☺️).