In the town of Yanabori, there lived many families, but there was one family that no one really understood. That was the Tsutsuki family. The man, Zero Tsutsuki, was a lab worker with more brain than most and his wife, Maria Tsutsuki, was a kind woman who could make anyone feel good. One day they had a child, a boy, named him Honda and raised him a lot of love and care. Four years later, they had a second child, another boy, who they named Gonta and raised with as much love and care as Honda. One day Zero`s intellect would backfire as he created a formula for a dangerous chemical, he hid so no one would find it, but his fellow lab workers found it and were impressed. This chemical, dubbed chemical Z, would make one stronger, faster and have stronger bones. After it was made, Zero managed to find a factory with tens of thousands of bottles of the stuff; he blew up the factory and thought that he and his family were in the clear. That was not true however; the other lab workers had tested it on a random robber and send him to the house were Zero lived. When Zero told his wife everything, she started yelling at him and they both agreed to make sure their kids were safe. Honda was eight years old and Gonta was four years old, he was sleeping while Honda got home from school to find his parents were not home. That night he heard noises from the back of the house and went to check it only to find a terrible sight. His father was beat up and bleeding badly "Run, now" he told his son only to be stabbed in the neck. Honda just stood there in horror and saw his dad fall to the ground, dead. Maria came from around the corner and saw her husband dead and her oldest son sitting beside the corpse, crying. The murderer went behind her and grabbed her by the neck. "Honda, sweetie, you have to…get out..off here, now. Please...take of yourself...and Gonta" she said. "But mommy, what about you?" Honda asked in tears and still horrified. Before his mother could answer, the murderer punched through her stomach. Honda, once again, stood and watched in horror as his mother stopped struggling and dropped to the ground. As the murderer left, Honda could only cry in despair. He told Gonta of this three years later, when he could comprehend it. At first Gonta was in denail, but soon enough he accepted it and cried on his brother, Honda doing his best to comfort him.

Since that day, things were never the same for the Tsutsuki siblings. Over the next nine years Honda and Gonta only had each other, Honda trained Ninjutsu, stealth, swordplay and thought Gonta what he knew just in case. The dojo Honda trained at wad going to be owned by Zero, but he declined opting to look after his family. Being the son of the "sensei" of the dojo, Honda got to train free of charge. After about five years he had mastered ninjutsu, stealh and swordplay. To make sure he didn't get rusty, he spared with Gonta every now and Honda was done with seventh grade, they left Yanabori and eventually found a Hotel they could stay at if Honda worked there. He worked there as a waiter and entertainer. Duringthis time, Honda found out that he was fond of playing piano. He became quite good and used it as a method of calm himself down. Gonta usually just did what Honda told him to, but when he was bored he just borrowed his brother`s phone. After four years they left once again and found an apartment that, thanks to Gushken, Honda`s new boss, they could now stay at. At the ages of 14 and 10, they saved a peacock from some people trying to kill it. Since then it`s followed them, they named it Befall. Despite never saying it, Gonta felt useless and tried to help whenever he could. He befriended Gushken's son, Ryutaro and gained some helpfull knowledge.

Update: Decided to give you some more insight on a few things and add a few more details.