Blind Cupid appears in the 2nd through 4th Chapters of the Void Quest within the Midnight Channel. It will attack and act as a healer for other Shadows in the battle. After being defeated, it may drop the Chirping Wings material. Selling 10 Chirping Wings at Daidara will unlock the Power Plate weapon for Kanji Tatsumi in the shop.
In Golden, it may also drop Lemon Quartz to trade at Shiroku Pub.