Aphrodite

The ruler of the tenshi kai, the goddess of love and beauty Aphrodite returns in Wedding Peach DX to give the Ai Tenshi new powers and support them whenever they need help. In Volume #1, Aphrodite explained why the Ai Tenshi are require to battle the akuma again:

    "There are devils who don't feel comfortable with the 
     peaceful settlement between the Angel World and the 
     Devil World.  Though few in number, they seem to have 
     come to the Human World.  Because of the influence of 
     their evil waves, the devils' descendants who were 
     asleep have begun to awaken..."

Aphrodite was also the one erased the Ai Tenshi's memories due to their requests. She later saved Momoko from an akuma and revived her memories as an Ai Tenshi. Momoko then, in turn, revived the memories of the others.