shotokan style
The Wado ryu Karate style mixes the two about 70:30 to karate but I'm not sure that is what your looking for. Are you looking for a specific style or anything that combines the two?
Daniel Larusso got taught Shotokan Karate in the Karate Kid
You can pretty much find any style of karate in Germany that you are interested in, including:Shorin ryuTang Soo DoTaekwondo!
Its an Okinawan style of Karate.
You would find the listings in many of the karate histories. The book Okinawan Karate: Teachers, Styles and Secret Techniques by Mark Bishop provides hundreds of senior practitioners and their lineage.
Each school teaches a specific style. There is no 'regular' karate. There are many similarities between all of the styles, with a few differences.
Wada ryu karate is a form of karate that has influences from all the main styles of karate, but the only differences are in the kata's. for example, the pinan's and unsu are from Wada ryu style.
American Karate is a style based on karate from Asia. It has been changed by Americans for various reasons, some of which is to approach the American style of fighting. There is also American Kempo which may be the same thing, depending on what school or system you are working with.
Japanese karate
That will depend on what it is you are looking for. If there is a specific style of karate, your organization is probably the best bet. If you are looking for karate in general Mark Bishop's book Okinawan Karate is a good source. Haines Karate's History and Tradition is another source.
It translates to The House of Shoto. It is a style of karate developed in Japan by Funikoshi, based on Shorin Ryu Karate from Okinawa.