Rurou no Tsuki

Synopsis

On a rainy evening, 19-year-old university student Saeki Fumi happens to meet 9-year-old Kanai Sarasa in the park. Although she is separated from her parents and lives with her aunt, she tells Saeki that she doesn’t want to go back to her aunt. Saeki takes Kanai Sarasa to his apartment where they live together for the next two months. However, Fumi is arrested for kidnapping and labeled a dangerous kidnapper as Kanai is seen as his victim. Fifteen years later, Kanai Sarasa and Saeki Fumi happen to meet each other…

(Source)