Ghost Hunt. It's old and a bit of a classic at this point, and despite being more about ghosts, there are actually plenty of IRL detective work. (There is even anime.)
It's a bit like Supernatural tv show before that show was even an idea, but not everything is because of supernatural things, and they have to investigate way more IRL stuff. But also, Ghost Hunt has a lot of text, because they actually talk about investigations etc.
And surprisingly not THAT tragic despite dealing with ghosts. Of course, when I read Ghost Hunt, the OG author of the novels had to take long hiatus, so I have read it only partially and not sure about ending other than spoilers. (I can't remember did manga go all the way to novel end, anime didn't.)
Tragic levels depend on people, but Shinrei Tantei Yakumo is kinda similar, but I think way more tragic.
If you want just detective stuff, not even hint of romance: Many of the mangas are just that. Especially a little bit older ones. It was a common troupe in almost in any genre for a long time, so if you just sort mangas (no manhuas/manhwas/webtoons) you should be just accidentally fall onto some detective stories. Japan have loved those since forever.
Does anyone have any story recommendations similar to this? Like mystery/detective stories(preferably not super dark and really tragic) with a female lead that’s not to heavy on the romance or by any chance has no romance?