Redo at past mistakes

An unknown attacker hits Akutagawa with an ability that de-ages him six years back to the age he was when he first met Dazai. Dazai being the only person Akutagawa knows at this ages, is forced with the task of looking after the fourteen year old until they can find a way to get him back to normal. As Dazai cares for Akutagawa, he reflects on his past and sees how he has a second chance to do better, whilst Dazai deals with his atonement, the task of reversing Akutagawa's condition get more difficult and things don't appear so simple as it seems.