SEOUL - A six-year-old South Korean YouTube star has bought a five-storey building worth 9.5 billion won (S$10.9 million) in one of the richest areas of Seoul.

The 258.3 sq m property in the Seoul suburb of Gangnam was bought in April, reported The Korea Herald. The purchase was made by the Boram Family, the company that operates her two YouTube channels.

According to YouTube analytics website Social Blade, the two channels - Boram Tube ToysReview and Boram Tube Vlog - hold the biggest share in marketing profits among Korean YouTube channels. The analyst estimated the average monthly revenue coming from the two channels to be around US$3.1 million (S$4.2 million).

Boram Tube ToysReview, which has gained huge popularity worldwide by introducing and reviewing toys, has 13.6 million subscribers, while the Boram Tube Vlog channel that shares the daily life of Boram and her family is followed by 17.5 million subscribers.

One of her most popular videos has more than 376 million views. It shows her making instant noodles using a plastic toy kitchen before slurping it down.

Last year, Forbes reported that the highest earning YouTube star was Ryan Kaji, 7, the American star of Ryan ToysReview. He earned US$22 million through his channel, which has over 20.8 million subscribers.

The YouTubers make money in numerous ways, such as through advertisements that play on their videos and by partnering brands to sell products. Boram sometimes links out to products featured in her video reviews.

Some of Boram's videos, however, have attracted controversy for the kind of values they promote, reported CNN.

Non-governmental organisation Save the Children received complaints in 2017 from viewers who were concerned about the staged videos that showed Boram stealing money from her father's wallet and appearing to drive cars on the road.

Those clips have since been taken down.