Based on mode competition, we propose a novel bistable device that has the potential to improve the degrees of freedom of optical input-output directions. Unlike conventional mode competition in a single cavity, the proposed device uses two cavities that are cross-coupled between an in-plane laser diode(LD) and a vertical-cavity surface-emitting laser(VCSEL). We calculated rate equations using the cross gain saturation model in order to find conditions wherein the proposed device could have bistability. We also analyzed the static and dynamic responses. From the calculations, we found that the product of the optical confinement factor and the photon lifetime of two lasers should have almost equal values. The results show that by coupling two cavities having similar characteristics, the switching characteristic becomes comparable to those of other reported bistable devices. In the case of static operations, switching powers of a few milliwatts and a few tens of femtojoules could be achieved; these are some of the smallest operational performances.