I read this novel a few years ago, and I enjoyed it. I wanted to find it again to read it, but I can't find it despite searching most places I've typically used to read BL Novels. It is a Sentinel and Guide BL novel, where the MC is a guide who works in a hospital, seemingly low-level. (I think he worked in the C grade department?) However, he had a high rating with a high-class Sentinel. I can't remember if he was a Marshal or someone of similar rankings maybe just not as high? Though he can help ease his mental issues and all that jazz. I can't remember much else other than that. Though I'm fairly sure that the MC was not transmigrated, nor was the ML. As a side search, If you have options for BL Novels of Sentinal/ Guide Parings, I'd also take a look. Even if it's one I've read before, I don't mind rereading the really good ones.