Where can I legally read manga online in Germany?
All though there are not a lot subscription based sites like Crunchyroll, The following sites do offer a broad variety of digital manga editions, which should have a lot less geo limitations. Which streaming sites like Crunchyroll do tend to have 


Bookwalker
Kodanasha 
Comicwalker
Viz 
Amazon


Considering that breaking the terms of service is not necessarily illegal. You could also buy yourself a VPN, and read the manga from a region where it is available, making it a semi-legal solution as well.