For the development of organic phase change materials (PCMs) that reutilize the thermal energy, an advanced heat managing polymer bearing phenylnaphthalene (PNP) side-chain was newly synthesized. The mesogenic PNP core introduces intramolecular π-π interactions to construct a thermal conducting polymer network and enhance shape stability. Highly ordered lattice structure of PNP restricts the molecular motion and provides a phonon transfer pathway, resulting in good heat transfer properties as well as excellent heat storage capacity compared with conventional organic PCM. This can be applied in advanced thermal energy-saving materials. This work was supported by Basic Research Laboratory Program (RS-2023-00207836) and BK21 Four Program.