Prosecutors indicted Park Yoo-chun, actor and former member of boy band JYJ, on charges of using drugs on Friday.
The 32-year-old Park is alleged to have purchased 1.5 grams of methamphetamine earlier this year and used the drug together with the granddaughter of the founder of a dairy producer.
Last summer, he is suspected of having taken the drug alone at his home in southern Seoul.
The now-jailed Park earlier confessed that he has used drugs since last summer and began to use the banned substances out of curiosity.
Hwang Ha-na, the arrested granddaughter of the founder and honorary chairman of Namyang Dairy Products Co., stands trial on alleged drug use on June 5.
Some speculate that they may stand trial together, given their charges overlap.
"Whether to review their cases together hinges on a court's decision and nothing has been decided," said a prosecutor.
In 2017, Park announced plans to marry Hwang after dating her since 2016, but he later called off the marriage and broke up with her in 2018. (Yonhap)