Mujintou de Elf to Kyoudou Seikatsu @comic

Kento (30 years old), won 1 billion yen in a lottery. In order to enjoy a nice slow life for the rest of his days, he bought a small uninhabited island off the coast of Southern Japan. However, one day he finds an unconscious woman on his beach that should not be there. When he runs up to check on her, he notices some rather sharp edges... The behaviors Elize brought from the other world are a little bit exciting for a normal guy like Kento...

(Source: TO Books, translated)