Where did Cobra get his psycho-gun?


In **Space Adventure Cobra** , a campy space opera series, and in its more
recent sequels, Cobra, the adventurous main character, has a cybernetic gun
embedded in his left forearm that uses mental energy. We know he wasn't born
with it, so how did he acquire the psycho-gun?

![Cobra and his cybernetic gun-arm](https://i.stack.imgur.com/OBHff.jpg)




He had made the blacksmith of "不知火鉄心 (しらぬい てっしん) (Shiranui-Tesshin)" who live
on the earth.  
thus, I think answer is the earth.

