If it says it's sealed...then that means you should have already beaten the game. Which is doubly strange if you say that you've just beaten the doppelgangers.
Verbatim, it should say "It seems that the portal is sealed now..."
In this case, you should be going to recruit Melody and Nayu. However, if you don't see a portal in the middle of Henesys that takes you to the The Path to Another World and it still says the portal is sealed, you should probably consult Zeru about it.
[9:22:39 PM] D T: ahdfs
[9:22:39 PM] D T: I somehow sneezed in my eye
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