The old man who found and raised Kenichi and taught him karate.    

(Source: Wikipedia)

When Kenichi Kokuhou was a small boy, he was lost in the mountains and never found. However, unknown to anyone, Kenichi has been brought up by his foster father in the wild. When Kenichi becomes 15 years old, his foster father tells him the truth about his background. As he finds out, Kenichi decides to go to a civilized society where his parents live. 
Everything Kenichi experiences in the town is a series of surprise and wonder. His family is delighted to see their son alive, but shocked at the fact that he has become wild and different from other children. And now, his new life is about to begin. 
His wild attitude and physical toughness cause various problems in the town. Kenichi has his own way to handle things, but it is too different for the most people to understand what he is up to. Can he get used to life in the town?

Having been raised in the mountains away from civilization for 13 years, Kenichi finally makes his return to the the city! His raw strength causes damage wherever he goes- not to mention, tons of laughs in this comedy like none other!
 
(Source: Weekly Shonen Jump Exhibition Vol.1 Catalog)
 
Included one-shots: 
Volume 17: Moeru! Oniisan (Pilot), Boku no Tomodachi P.2 
Volume 18: Super Otousan

Cha Genmai