8-gatsu no Nikki wa Lazurite

A beautiful boy with pure eyes suddenly appears in front of Makoto, a female university student living alone in a rundown apartment that has been scheduled for demolition. Makoto ends up living with Tenran, a boy with a troubled past who has an otherworldly sense of money and a brain that rivals adults, for just one month during the summer vacation, on the condition that he helps with living expenses...!? (Source: Hakusensha, translated)