[en] We constrain the true spin–orbit alignment of the KOI-89 system by numerically fitting the two Kepler photometric light curves produced by the transiting planets KOI-89.01 and KOI-89.02. The two planets have periods of 84.69 and 207.58 days, respectively. We find that the two bodies are low-density giant planets with radii of 0.45 ± 0.03 R_jup and 0.43 ± 0.05 R_jup and spin–orbit misalignments of 72° ± 3° and ${73}_{-<!--\; ???\; -->5}^{{}^{\circ <!--\; ???\; -->}+11}$, respectively. Through dynamic stability tests, we demonstrate the general trend of higher system stability with the two planets close to mutual alignment and estimate their coalignment angle to 20° ± 20°—i.e., the planets are misaligned with the star but may be aligned with each other. From these results, we limit KOI-89's misalignment mechanisms to star–disk-binary interactions, disk warping via planet–disk interactions, planet–planet scattering, Kozai resonance, or internal gravity waves.