Yuuka-chan is there with Lucifer right from the beginning. She becomes their manager, and is instrumental in getting them gigs. She runs their publicity, books them gigs in clubs, and acts as a peacemaker between band members when they argue. She seems to understand Sakuya more than the other members of Λucifer.It is known in the manga that Atsuro and Yuuka have a long-time relationship Yuuka, is actually his stepsister with whom he desperately tries to keep their relationship a secret from their parents, the media, and even his band mates. Towards the end of the series, his whole band (except Sakuya) reveals that they had known of their relationship all along. Also by the end, Atsuro and Yuuka also make a conscious decision to be open about their relationship to the public.Yuuka is Lucifer's die-hard supporter, and travels with them when they go on tour.She is always cheerful and supportive, and worries about Atsuro when he gets in an argument with their parents. She wants to become a good manager for Lucifer, so she leaves the band to go study Business abroad.