no moral
Read these two in this specific order, tho not a sequel they're kinda connected, also don't be put off by the art at the start, it changes for the better in just a few chapters :
Song of Reverberation
https://www.mangago.zone/read-manga/song_of_reverberation/
The Promise
https://www.mangago.zone/read-manga/the_promise/
also this list has some great plot focused bls but some might be smut so choose as you like
https://www.mangago.zone/home/mangalist/2758080/
Bongchon bride
The beauty and the west chamber
Both of them are best for your description
aka, shounen-ai. I just want to focus on the plot.
Plot heavy yaoi is also accepted.
Tank you