New Delhi, July 2 -- When he wanted to give a gift to his father who sacrificed much to raise him as a single parent, Lee Geon Hui settled on an unusual idea: an AI-animated video message from his late grandfather, whom his father misses dearly.

Lee wrote a message and hired the Seoul-based tech company Vaice in December to make a short video clip showing a digital likeness of his grandfather delivering it. The virtual character called his father "my most precious son," and apologized for making him help with farm work when he was a child and for opposing his son's decision to become a hairstylist.

"My father said he wouldn't watch the video. But then he did, and he shed tears. So I felt rewarded," Lee, a 28-year-old office worker, said...