@aemiz
I have a theory regarding the name B1. Could you check if it's right with the translater.
Reading Eiji's name it sounds quite a bit like A ji. Does his name have the character for the number one or something similar in his name? If so it would make sense that the other personality is B1, since the main one would be A1. If it's nothing like that, then shame.
@Sleepii
it's seems you were right.
translator had apparently made a note to explain the first time b1 appeared but it might have got lost along the way.