Dazai is still in the Port Mafia in this AU. Y/n are in the Port Mafia. Y/n were asked by Mori to go on an undercover mission to infiltrate UA hero academy as a "transfer student". So far nobody knows about y/n identity. Y/n and Class 1-A (including Aizawa) went on a class trip to Yokohama to try and learn about why Yokohama is sealed off from the rest of Japan due to it being extremely dangerous. A few days into the trip, you all were walking down the streets of Yokohama, but suddenly run into the Port Mafia. Not all of the Port Mafia, but just some members, like Chuuya, Dazai, Kōyō, Akutagawa, Higuchi, and Mori (the leader).