Stumbled upon a thrilling alternate history anime called Konpeki no Kantai (紺碧の艦隊) some while ago. This OVA deals with a technologically more advanced IJA/IJN thanks to Admiral Isoroku Yamamoto who was somehow teleported back to time or to a parallel universe after Operation Vengence in the first episode of the series, thus retaining his old surname Takano. Using his advanced knowledge of the future and superior technology, the events of World War Two were radically altered in Japan's favour, but interestingly enough however, the Japanese Empire, being part of the Allies later on, clashed with Nazi Germany. In the spin-off Kyokujitsu no Kantai (旭日の艦隊) the IJN faces the formidable Kriegsmarine in the Atlantic. Note that the given names of non-Japanese personaliies are changed whilst they still retain their correct surnames.
All episodes of Konpeki no Kantai here: 旭日の艦隊 - YouTube
Can't find any full Kyokujitsu no Kantai episodes though, sorry.
Plus, no English dubs or subs exist as it is not meant to be released outside Japan. But even if you don't speak Japanese, take a look at this awesomeness. 
@Nihonjin1051
All episodes of Konpeki no Kantai here: 旭日の艦隊 - YouTube
Can't find any full Kyokujitsu no Kantai episodes though, sorry.
Plus, no English dubs or subs exist as it is not meant to be released outside Japan. But even if you don't speak Japanese, take a look at this awesomeness. @Nihonjin1051
