Is karate really useful?

Karate is not bad. It is a practical skill in Japan.

Karate is a combination of ancient fighting techniques 500 years ago and boxing techniques introduced from China. At that time, in the high society of sulfur ball, China's boxing was secretly referenced, creating a unique Tang-style player, that is, the original "karate". Before the Tang Dynasty, there were two names, "Na Zhe Shou" and "Shou Li Hou", which were divided by region and became the origin of various schools of karate today.

With proper training, you should be able to deal with gangsters.

However, it must be noted that punk can't speak bushido. He may use a knife and a gun against you. So use tactics.