Gamegodtre said:
it takes place 10 years after P3 in a alternate universe of said world. That's how its related.
the thing that gets me is that it isn't dubbed into english. Also at the end of P3 didn't you destroy all the shadows i don't remember been to long since i beat it.
Apart from Igor, there is nothing linking Persona 3 and Trinity Soul. Persona's aren't summoned by an evoker (p3) or acquired by overcoming one's weakness (p4) so it just doesn't feel the same as the Persona games to me.
Also, I think you destroy the Dark Hour at the end of P3, not the shadows. Shadows and Persona are 2 sides of the same coin after all and shadows still appear in P4, which also takes place in the same universe.