Unlock Seraphic Gate:
     Finish  the game, watch the credits and save when prompted. Go to
the  main  menu  and  select the unlocked new options to access to the
Seraphic Gate dungeon.

Unlock Character art:
     Go  to  the  "Voice Collection" menu and unlock all entries for a
character  Highlight that character, after that press Square button to
view thier art.

Get Tri-Emblem:
     Finish the Seraphic Gate dungeon by beating Iseria Queen

Unlock Book of Riddles:
     Finish  the  Seraphic Gate dungeon by beating Iseria Queen 2 to 9
times One book (8 total) will be awarded each time.

Get Angel Slayer:
     Finish the Seraphic Gate dungeon by beating Iseria Queen 10 times.

Secret scene:
     Finish  the game with the "A" ending. When the credits end, there
will be a scene involving Bramms and Lezard.