Krulcifer first met Lux when she confronted him after the bathroom incident. While seemly praised him for being a cute peeping tom, she believed that he should be punished. Krulcifer began to seriously fall for Lux after he listened to the story of her origin when they were separated from the investigation group inside the ruins. Lux insisted that Krulcifer is a friend and not just a 'survivor of the ruins'. After Alterize returned to Ymir, Krulcifer expressed her real feelings for Lux by kissing him twice on the lips.