Lucy was the last born of hthe siblings, she brings the brothers together after Lilith deaths but suffer loneliness after her big sister death. And that she became really quiet, but... after someday she began to speak and talkative again since she got a new hobby and wanting not to think abt the past event. Yet she often forget how to control her power that is the 7 deadly sin. So the brothers teach each of their sin so that she csn control it... years pass she still can't control it until MC came to teach her properly.