The evolution of love could only be done by the goddess of love with a person that has a really close relationship with her. In the Kamichama Karin Chu, Karin does the evolution of love with Kazune most of the time, and only once with Michiru. In the end, she also does it with Jin. One time, Rika kissed Kazune so Karin wouldn't concentrate. The Evolution of love is an upgraded form of kamika.
The attack Karin and Kazune uses is Love Caelum. The attack Karin and Michiru uses is Love Thalassa. The attack Karin and Jin uses is unknown. There is also another kind called the Family Evolution of Love. It is used by Karin, Kazune, and Suzune, their child.
Karin and Kazune's Evolution of Love
Karin and Michiru's Evolution of Love
Karin and Jin's Evolution of Love
Family Evolution of Love