I know only 1st is in english, although there are translation projects on the other 2. what is the difference between em? Are 2 an 3 played from different characters perspective. is the story essentialy the same, whats the difference.
The 3 games storylines happen at the same time (but Scenario 3 starts somewhat by the middle of Scenario 2).
If you play scenario 1, you'll encounter Medion and his troops(scenario 2 main character) sometimes. In scenario 2 you also see those encounters, but in Medion's perspective (and Symbios actually say something).
The final battle for all scenarios happens in paralel, in Aspia. But you get to play an extra chapter (the Final Chapter) in scenario 3 if you use the save from the previous scenarios.
Gamefaqs.com has a FAQ for Scenario 1 with the complete timeline for all 3 scenarios, and the link between them.
you also find that doing certain actions in one scenearo affects another (eg in the 1st theres a guy tied up who runs away if you free him, if not he sits there and dies) if you free him he joins the party for either scenearo 2 or 3, and if not someone else joins in his place
you can play any of the 3 sepeately though, just without any knowledge of japanese its kindof pointless to do so