To y'all asking for the sauce,
the character is Juza Hyodo from a mobile game called A3! I haven't played the game myself but it doesn't seem to have any themes of medieval-fantasy, quite a shame. It only looks to be an outfit change.
https://yaycupcake.com/a3/index.php?title=Cards/Juza_Hyodo/Brave_Adventurer
This manga is getting better because it's getting more toxic lmao most of manga have healthy and dreamy relationship so this one is definitely a good reminder of the 'reality'