I want to learn Jiu Jitsu (not BJJ). I know that BJJ can be better, but i'm not interested in that. I'd like to know which school in Japan is to learn original Jiu Jitsu. The place can be anywhere, but in Japan.
Traditional Japanese style is referred to as "classical jujitsu". It's also known as "Samurai ryu" (Samurai schools).
And note that the spelling tends to be "jujitsu", not "jiujitsu". The latter spelling is mostly now used to refer to Brazilian Jiujitsu. But it still can be used for classical jujitsu, depending on the country where it's used. Just not as often as "jujitsu". And there are some purists that spell it "jujutsu".
Anyway, there are many kinds of classical jujitsu. Some are more modern, some are very old. The styles vary quite a bit, in terms of postures, philosophy, fighting range, ground technique vs. uprightness, whether or not it was developed for battle vs. developed for self-defense, etc. Literally, each one of these jujitsu schools are an entirely different martial art in themselves. Many even resemble kung-fu styles.
So it's actually pretty hard to answer your question. I think you just need to do some research. Look into lists of classical jujitsu schools, and then read up about their particular philosophy. With any luck, you'll be able to see their techniques on youtube. And from this, you can get an idea of what might interest you. After that, you should go and check them out in person. Show up at their dojo and ask to view a class or maybe have an introductory lesson, if possible.