When Atsumu and Osamu were just 14 years old. Their mom and dad took off, leaving them with their 2. 3 year old siblings to take care of. Akira (girl) and Aki (boy)

Their aunt gave them a house to stay at for free, no rent, but was never around, so Atsumu and Osamu had to figure it out. Atsumu did most of the heavy lifting, considering his the elder twin

They applied for the Child-Rearing Allowance and got it so that helped with bills, Atsumu got a bursary for volleyball in highschool and so did Osamu which also helped with expense as the school gave them some money, Atsumu and Osamu also had part-time jobs

Now Atsumu and Osamu are 18. They're parent are back like nothing happened. Like they didn't abandon them and leave them with nothing