I'm trying to recall the title of an animated movie I watched as a kid long ago. I'm not even sure it was a movie (though if it was it's probably an animated one), but I remember I watched it on TV. The plot is sort of as below, where (xyz?) denotes parts that I'm not sure and could be something similar.
There was a legend of two close brothers in ancient times, (who were strong warriors?). Something happened and one of them (died?), then no one heard of the other. It was believed that (either the two were immortal, or the surviving one turned immortal in that event?).
Some 3000 years later, a group including the protagonist is trying to solve some (mystery?). Investigation relates it to the two brothers' legend, then one in the group figures the survived brother should still be alive and probably has accumulated a lot of wealth. It turns out that brother did become very rich and currently the owner of a huge/very powerful corporation.
He has been preparing for an upcoming significant event, which hasn't happened for at least 3000 years (and also is the chance to revive his brother?). The group (tries to stop him?) for some reason.