A very brief post today. The birthday song in Japanese is sung to the same tune as the one used in English/the West.
“Happy Birthday to You”
お誕生日おめでとう
otanjoubi omedetou
So, would come out as:
“Hap-py birth-day to-you!”
“o-tan-jou-bi o-me-de-tou!”
Very straightforward!