Tosa has been known in Japan for almost a 1000 years by now. He was bred as a fighting dog, so he’s probably not the best choice for an inexperienced owner. This breed is normally a well-mannered and peaceful dog for his family, but it has already shown aggression towards other dogs in some cases. He is reserved with strangers, but not necessarily aggressive to people. This breed is definitely a fearless protector and guardian dog. Tosa can behave well with small children if he gets very early training and socialization, but rough play should be avoided because of his fighting instincts. Tosa is intelligent and very easy to be trained. He has a low energy level. The average weight of this breed is 100 to 200 pounds, and its size is about 22 to 24 inches.