x0unerthanlater
`my dragon's blood is blue`
A lot of times (don't know if it's factual) spirits/ghosts who die a traumatic death will keep lurking around the area they died or keep doing something they were supposed to do right before they died. For Rin, her last concern was she had to perform. It is also something she's really attached to. She loves dancing. That's why as a spirit she's doing 2 things. She keeps dancing near her grave AND she's keeping watch over Taechin. These were (and still is) the 2 most important "things" to her.