Nosebleed/ headache- Akaza
When Muzan got mad he got really mad. And Akaza was usually the victim of him letting all that out.
Akaza knew he was in for trouble after he'd failed to beat another Hashira. He knew Muzan must have seen it, he sees everything. And Muzan did not let that sort of thing slide.
That's when the pain came.
From somewhere deep within him, something just felt wrong. He felt something on his face, so he wiped it only to see blood on his hands. Probably smeared all over his face now too, he felt fresher blood pouring out his nose. There wasn't a doubt in his mind on who was behind this. Muzan had a thing for this sort of stuff, making the injuries internal so there was nothing they could do but suffer through it. Akaza kept trying to wipe it away only to realise that the blood wasn't going to stop and Muzan was far from done. The entire bottom half of his face was probably covered in red by now. It was like a bloody waterfall on his face. He'd have to wash that off later. Still, Akaza tried to tough it out. Simply giving up and crying was not an option for upper 3.
He still continued on his walk, trying to distract himself from what was happening to him and what was going to happen. His head started to ache, it felt like he'd banged it on something. It was the quickest way to get him in a bad mood. Pain erupted right from the centre of his brain. It was unbearable. He tried to argue to himself that it was only a headache, but he knew that he couldn't lie to himself. He wanted to smash his head against a wall until it stopped hurting. His whole head was practically at war with itself, aching like mad and wanting to wreck itself. He just wanted it to stop.
Muzan sure knew how to torture because right now his whole head was in a state. With his head spilling blood out his nose at an alarming rate and his brain at odds with itself. He couldn't focus on anything else, still, he refused to let it show. The blood from his nose was now pouring down his face in large amounts. And at this point he was too fed up to even do anything about it. it was a waiting game now, just to wait until Muzan got fed up. and that would take a while.
Eventually the blood and pain got to much. He jumped in a river to wash up all the blood that had covered his face and chest while he waited for Muzan to calm down. The red liquid was already beginning to dry and stick to his skin, his nose still ran with it though, feeling like he was feeding the river a permanent supply of blood. He screamed and cried out in frustration. But Muzan never was known for his kindness. Even long after the event, he still panicked just a little when he got a headache.