Bronz_Deck
Besides, if he becomes a demon he will no longer be able to sell his products freely, because he would no longer be Akira Gojo, a human alchemist, he would be Akira Gozo, the servant (slave) of Rias Gremory, and apart from that, the devil race has its policies with its council. and he is just a reincarnated demon, his statue would not be good. And to sell his products to other factions, let's not forget that these are international affairs since he serves a faction and does not work alone
Really hope the MC is smart in setting up the ground rules. He "agreed" to join her peerage, but not to obey her. If they're going work closely with each other, she needs to have EVERYTHING ironed. So a contract, which everyone in the peerage and are present said signing, for his employment and digression should be the bare minimum. Rules would include using the door rather than teleporting in unless someone's been abducted or someone will die very soon. A steady supply of corpses and ingredients for his experiment and research. A regular source of income. All contractors that he is assigned to must provide information on appearance and any prior involvement in the supernatural world. (Mil-tan precaution) If he solos a stray Devil, he collects the bounty and he chooses how to dispose of the body. Whether by disintegration or scrapping it for alchemical parts. Any events (whether it's political/medical/public/etc.) that require his presence must be sent two weeks prior to the event itself. Anything the King finds out about the employee's research portion or the nature of their abilities will remain secret and will not be used as blackmail nor will said information be revealed to gain favor from parties that didn't sign a a magically binding contract written out by the employee in question. The King must receive consent from the employee in the event the King demands it's members to train, while the King themselves must also train their magic and/or body.
This brings up an interesting point, This isn’t an evil Rias, she genuinely wants her peerage to be an extension of her family or friend group at the very least. Would she reincarnate someone who was living fine as a human with no desire to be a devil before her brother basically threatened them into joining? Or will that stay secret until after Riser so that Rias can chew out Sirzechs for making HER Akira’s Riser