Quick answer — Quadrangle performed 1 anime theme, including "PARADOX" from RErideD - Derrida, who leaps through time.
Quadrangle performed the anime theme songs "PARADOX" (RErideD - Derrida, who leaps through time).
Quadrangle's first listed anime theme is "PARADOX", the opening of RErideD - Derrida, who leaps through time.