18+ Oneechan ni Omakase

Book from mangaka Jamming that includes the 5-parter title story, Leave It To Sis. The story deals with Yuu and his dilemma of having his older sister Nanami taking a way more than sisterly interest in his sex life especially when concerning his situation with his girlfriend Sayaka. Yuu gets more than just sisterly advice from elder sister Nanami and two of her closest girlfriends.

The book also includes two additional supplementary stories: Kamyla and the two-parter titled Alucard.