Did a little digging on the Agarest Wiki:
A new system is introduced called the Feel Link System. The Feel Link System is where the heroine's costume, and dialog depend on their relationship level.
Another new system, players can build relationship with the heroines. This may result in new costumes,CGs, and items. This is accessed by the City Menu. These costumes have been confirmed - Maid, Shinto Priestess (Miku), a Nurse and School Uniform. This is not limited to the Love Interests.
Normally I don't say something like this but...Ar Tonelico rip off much? (Although I'll admit if it actually does what it says it does, and the things that prompt alternate costumes are actually meaningful without being simply "best answer" nonsense, it could actually be superior to the AT system.)
Also; a quick Google search through images reveals that even though this is a "prequel" they're taking the double or nothing approach that sequels do and giving us a one-up of the ridiculous sausage image from last game. Only this time it's two girls and one unbelievably oversized banana...*bangs head into wall repeatedly* Exactly when did Japan lose any and all sense of the word "subtlety"?