Fight Taboo Sho (Tipsy Tose Hall, W2D2) on Hard. Base drop rate 1%. OR: If you do use ultimate mode.. In the Shibuya Q-HEads they are available for 10 shadow matters after befriending the shopkeeper. (shadow matters are though obtained from the taboo noise on ultimate mode... still a bit easier then a boss on hard) Easiest way to get dark matter: Fightr reaper beat on ultimate