South Korean actor Song Il Gook's son
A screengrab from the video

South Korea's most beloved triplets turned five on Thursday and they celebrated each other's birthday in the cutest possible way ever. Song Il Gook has shared a video of his sons Daehan, Minguk, and Manse, who were born back in 2012, singing a song together.

In the video, the kids are seen singing an energetic rendition of "Happy Birthday" in Korean to each other with several false starts, before finally blowing out the candles on their individual cakes. While singing the song, Minguk politely asks: "Is it okay if I eat the chocolate (on the cake)?". The question is echoed by his brother before all three are given the go ahead to dig in.

Ever since the video was posted on Instagram, it has racked up more than 530,000 views and 21,000 comments with fans both in Korea and overseas sending their well-wishes and fawning over their cuteness.

The trio shot to fame after appearing on the KBS reality programme, 'Return of Superman' from 2014 to 2016. They starred in the show alongside their dad. A 2015 report showed that the triplets were the fifth most popular celebrities in South Korean advertising. Together they draw a whopping amount of $4.26 million in endorsements.