What if the Otomo Unified Japan?

Through Portuguese support, some cheeky Total War Tactics, and other things; let's say the Otomo Clan unified and converted japan into a Catholic Shogunate.

Do you think it was possible? If so, what might be the future of Japan?

Woah! Interesting. I love learning history through contrasting it with Alternate History. Unfortunately, I don't know much about the Shoguns except that scene in the movie where the one warlord pisses down the back of the captain. Oh, and the scene where the Japanese chick gets naked and takes a bath with the captain. Can't forget that.

I'd really like you to elaborate on your own speculation of how the timeline might be altered...