BL or GL with actual plot. Romance must be secondary genre. I’d prefer if it was horror ...

How about apocalyptic setting with researcher turning to find out who killed his mentor and a loyal military officer with a crazy attitude.
“Rainbow city”

Oh and “little mushroom”

Ty

https://www.mangago.zone/read-manga/timeless_melody/

https://www.mangago.zone/read-manga/life_senjou_no_bokura/

https://www.mangago.zone/read-manga/a_shoulder_to_cry_on/

"The summer hikaru died" is an ongoing horror mystery about yoshida who's discovered that his childhood friend (one sided crush) Hikaru has been replaced with a creature that's taken his memories and his appearance. The mystery is why and how this happened.

"Her shimcheong" is a historical drama slow burn yuri about a beggar girl teaching a newly wed noblewoman how to nurse her sick husband. The story has some really good drama as the girls must interact with and use the social norms and standards for women to their advantage and their disadvantage.

Ty