The name Benben means "valve, dialect, discrimination" (弁).
Benben's surname Tsukumo means "ninety-nine" (九十九).
Her family name "Tsukumo" comes from "tsukumogami", her species of youkai. The motif of hers might be derived from "Bokuboku Biwa" (琵琶牧々), a tsukumogami transforming into biwa houshi.
Fun Facts
Benben and Yatsuhashi shares the same ability (making music of their own), like Cirno and Letty Whiterock who shares one ability (Ability to Manipulate cold/chill, even their level is different.)