Kei is the adopted daughter of Benkei Kuruma. She holds a secret about her origin due to a mental block that was present when Benkei adopted her. Kei always attempts to look and be strong but is actually rather vulnerable due to holding so many suppressed memories. This started after the death of her older sister Michiru which caused Genki to close herself off from everything. By the time so much destruction happened around her along with her past traumas.