CALL OF THE NIGHT: PARADISE ARC

Anko and Kou are assigned to investigate a mysterious religious cult called "Paradise", after Amu Miyamoto from the idol group "Wednesday is Sunday" reaches out for assistance. Her fellow band mate, Mei, is entangled with this sect. The group's enigmatic leader appears ageless and perpetually radiant, hinting at a vampiric nature. Their arrival in the secluded countryside where "Paradise" is based is met with suspicion and hostility... and thus, the pursuit kicks off! — Description from AniList community (anilist.co).