The duo was composed of sisters Shuuka and Karen Fujii (hence the sub-unit's name), making them the first joint unit of members from the groups Flower and Happiness.
[2] The sisters would promote with this sub-unit whilst carrying on activities with their corresponding groups E-girls, Flower (Shuuka) and Happiness (Karen).
It was also revealed that both girls would be singing, making this the first time Shuuka would be providing vocals for an official project since her debut (as a performer) in 2011.
[3] Though it was the sisters' first musical release, they did work together prior to the formation with a fashion book, titled Antithese, which garnered critical success and sold over 100,000 units in Japan.
[8] On September 24, the duo starred in their first TV commercial for a new candy product from UHA called e-maのど飴 モーフィング together.
[12] On December 31, Shuuka announced to have graduated from the unit and retired from entertainment industry due to worsening symptoms of cervical spinal disc herniation.