When Atsui was 13, her father sexually abused her which caused her to get pregnant and call the police on him.
After she gave birth to Atsushi in 2010, her father escaped from prison and killed her. Before that, she transferred her humanoid tiger ability to her son while abandoning him at the Yokohama orphanage.
Atsushi suffered from verbal and physical abuse from the headmaster/caretakers. Because of this, it has taken a huge toll on his self-worth now that he's older, causing him to constantly question the value and usefulness of everyday life.
When Atsushi turned five years old, the nun told him that she met his mother after he was born. After the conversation was over, his caretakers suddenly stopped feeding him.
Alongside the caretakers' verbal and physical abuse, Atsushi also suffered at the hands of the other orphans as well.
They'd often throw him off of the bus as it drove in the street, he would cry for help for Akiko to get off of the bus to bring him back in it. One of them even cut his hair as a prank and he had to let it grow as the hairstyle that he currently has.
After his mother passed away, Dazai reincarnated her into an 22-year old woman in the ghost temple and became Chuuya's caretaker at the Yokohama orphanage.
One day, the headmaster nailed Atsushi's foot with a hammer and Atsui took him into the infirmary to pull it out.
"Thank you so much." Atsushi said.
"You're welcome, my son." Atsui replied.
The two of them realized that they're related to each other, and hugged all the way to the cafeteria to eat dinner.
THE END