Board Thread:Questions and Answers/@comment-30575144-20150831175352/@comment-26157862-20150901091035

 In addition to Goddess of Rare Drops, you can also give  全員レア追加報酬率 (Gives "lucky" effect to all members)  to NPCs (since it affects the whole team anyway) and for Back-up characters like Teru, Rikka, Yuno, etc. you might want to try adding  報酬確率↑ (Increases reward chance),  結合崩壊報酬追加 (Increases unbound reward bonuses), and  条件無視:結合崩壊 (Ignores unbound condition, so you can get a certain drop even without unbounding the required part) and  支援効果発動+1 if you want so you can choose more support skills ^^ Of course the drops aren't always certain, but these certain skills really helped me a lot in obtaining a lot of drops for upgrading weapons ^^