Are you looking for a direct translation or inspired by?
Inspired could be as simple as the barbarian raging (rage is a trapped demon inside)
a pretty close literal way would be a bloodrager draconic bloodline black dragon for 5 levels and then dragon disciple.
Easiest way is if the gm would allow you to use a summoner synthesist that would allow you to make a body with wings and claws and you would be stronger when fused to it
Do you have any recommendation for the class/race and feats-traits?
Have you looked at the Shifter's Fiendflesh Shifter archtype? I know the Shifter class is a bit crap and there's a specific limitation on this archetype requiring you to be evil but if your looking to make a character heavily influenced by another your not looking to play optimally in the first place and your DM might be willing to overlook the evil requirement and instead say you've trapped it within your character and are channeling bits of the demons power. My DM watched the newest anime and gave me the go ahead for it on a character so maybe yours will be as understanding as well.
It also helps that the fiendflesh shifter practically has everything you need to roleplay Akira built in with the form change. Only thing it seems to really miss is that fire ability he got in the later episodes.