In recent years, with rapid climate change emerging as a global concern, the urgent development of technologies for the effective utilization of renewable energy has become paramount. Currently, thermal storage materials have garnered attention as one of the solutions to this challenge. Generally, phase-change heat storage materials face limitations in the long-term preservation of energy. However, if there were materials capable of retaining accumulated thermal energy and releasing it upon external stimuli at desired timing, the potential applications of thermal storage technology would significantly broaden. From this perspective, we have proposed externally stimulated responsive thermal storage materials. These materials can store latent heat within until the addition of external stimuli. This article explores long-term thermal storage ceramics composed of lambda–trititanium–pentoxide (λ-Ti3O5), providing details on their synthesis, thermal storage properties, and potential future applications.