Hotaruko

They have in common that they start with an outsider arriving at a village or an isolated island, where families have lived for generations who have never left their homeland, with dark traditions and secret rites. In both there is gore, the Hotaruko Crimson Climax is a hentai 

-Same studio -Very similar art style -both have nudity and gore although hotaruko is full on hentai -both are horror anime 

+ MC is a descendant of The Family who inheret Black Religious Clan + Some lesbian sex scene + MC isolated from outside world + "Flower" also become main problem in both anime 

+ Both hentai tell story about heresy + MC originally normal people but later corrupted by darkness power and turn become antagonist (Kurumi Imari & Ryou Inasa) + Alot lesbian, sex, gore, & blood scene