If you loved Hello Ghost, try Slow Video
A bridge between a film you've already seen and one most people haven't. Slow Video has roughly 5.8× fewer votes than Hello Ghost — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Kim Yeong-tak, and they sit in Comedy / Drama territory. If that's the register that drew you to Hello Ghost, the second film will land in a comparable space — through a different lens.
What Slow Video is
Here's a film about a superpower that seems more trouble than it's worth. A young man with the ability to see everything in slow motion uses his powers working at a CCTV control center. He then attempts to use his surveillance skills to woo a woman. It's hard to say if this is sweet or creepy, but it's certainly a premise.

