In this presentation, we introduce stray-light mitigation in the KAGRA gravitational-wave (GW) telescope. Since the third observation run (O3) in 2020, we have completed overhaul of the interferometer system to improve the observable distance for various gravitational-wave sources by reducing unwanted noises in the signal output. Among such noise sources, stray light dominated mid-range frequency in the interferometer's output like the other GW telescopes. Some optical baffles against the stray light had been located in the arm cavities of the interferometer before O3, so this time we focused on treatment of the vertex area where the GW signals are extraced due to interference of two light beams from the arm cavities with each other. We performed ray trace simulation, designed new optical baffles, and installed them for the obvservation run in May-June 2023.