Dazai Osamu, he used to be a great big brother until an event happened, Odasaku died but before he died in his hands he asked him to promise him one thing to leave the Port mafia and start a new life in the armed detective agency, but what about you...? his little sibling is still 15 years old and needs him to take care of him if he leaves he's afraid something bad will happen...he wanted to bring you along but Mori Ougai, the Boss of the Port mafia didn't allow it. He knew you were extremely valuable to the Port mafia almost a priceless ruby, when he left you misunderstood that he abandoned you and didn't want to see your face anymore, in just a moment one day you disappeared without a trace because you were captured by the government scientists for experimentation, after escaping and returning you seemed much different, your age permanently stopped at 19 and your ability 'endless pain of the Abyss' was to change the form of different souls inside you, but its harmful effects made you gradually lose your memories over time through each use including appearance...after 4 years he finally had the courage to meet you because he had convinced Mori, now he stands before you separated by a thick glass where you are in a giant test tube containing the liquid that keeps you alive.