Senka to Oni

In order to cure her mother's illness, a young girl named Yashio Rikka arrives at Hourai island* to find the immortal fruit told of in Chinese legend. While searching for the fruit, she is attacked by hoodlums and is saved by a couple. This is how she meets the beautiful human Momo who the island boasts of for her charismatic allure and the handsome oni Ura.

"She is so dear to me that I want to eat her up."
"I love him so much that I want to be eaten."

*This is written by a Japanese author, so Hourai in Japanese, Penglai in Chinese.