Utopia

Summer vacation.
While Mayu's parents went on a trip for their wedding anniversary, she stayed home alone. Though she felt like she couldn't be bothered to, she went grocery shopping and when she came back home, there was a strange boy in her house. He introduced himself as Lucia and said he was an angel. Although she found it unbelievable, she was somehow persuaded to start living with Lucia.

[Translated from official website]