Yeah for the purpose of this story I chose to do it like that - I put a note at the start letting ppl know. I decided to do it that way bc I wanted Dazai to call him Oda like he does in canon and it wouldn't really make sense for him to call him that if he used to also have that last name so I just flipped it. I hope it's not too annoying!! It bothered me a bit too but something felt off no matter which way I went about it 😅