this reminds of that manwha where there is the modern time in season 1 AND the historical stuff in season 2. Maybe "The dawn of the dragon" (?).
Uke was strong and buff just like here with a crybaby seme (though, susssssssss on their weird dynamic when they first met during their past lives T-T, uke taking care of the seme since he was a child and uh- sudden growth spurt, now lovers?! ehhhhhhhhhh, modern era is not with that bs but man, why that dynamic when they first met?).

Delivering all this plot while SIMULTANEOUSLY CRACKING. This is truly the best of both worlds. I do hope we get back to the modern world though, all this historical stuff almost had me forget this started off as a modern day romcom set in college