CANDLES -- Search for Neutrino-less Double Beta Decay of $^{48}$Ca

CANDLES is the project to search for neutrino-less double beta decay (0$\nu\beta\beta$) of $^{48}$Ca. The CANDLES system aims at a high sensitive measurement by a characteristic detector system and $^{48}$Ca enrichment. The system realizes a complete 4$\pi$ active shield by immersing the CaF$_{2}$ scintillators in liquid scintillator. The active shield by the liquid scintillator will effectively reject background events from external origins. On the other band, we have studied $^{48}$Ca enrichment and succeeded in obtaining enriched $^{48}$Ca although it is a small amount. Now we have developed the CANDLES III system, which contained 350 g of $^{48}$Ca without enrichment, at the Kamioka underground laboratory. Two improvements, a light-concentration system and a new DAQ system, were installed for the CANDLES III system. The light-concentration system improved a energy resolution by increasing a PMT photo-coverage by 80\%. The new DAQ system, which is a dead time less system, improved a rejection efficiency for a characteristic background origin. We checked detector performance with the light-concentration system and the new DAQ system. Here we will report the detector performance for background rejection and the expected sensitivity with the two improvements.