The manga is about a high school boy who learned boxing from reading a book. Later on in the manga, he started fighting gangs and earned the nickname "Gang Destroyer" or something like that. He lived with his father, mother, and sister, and they had no idea that he was the Gang Destroyer.
Please help me figure out the name of this manga T_T
This is probably Holyland. It's manga about boy who was bullied and learned the one-two combo (a jab then a cross) from boxing book to get revenge. This drew attention of underworld, which got him into new fights and forced him to get better at fighting.
It is shown in earlier chapters that his only move is the one-two combo. Even his stance and his footwork were that of an amateur. However, he managed to defeat thugs with his only move and earned him the nickname Thug Hunter/Gang Hunter among the street gangs and drew their attention.
The background story on how he learned the one-two combo, and even the fact that he learned it from a book, was only revealed in chapter 12 to chapter 14.
