Kokoro No Tobira

When you were a child, your younger sister was hospitalized and, while she was sick, she asked you to create your picture book for her. Time has passed since, you're both in school, her illness is gone, and the graduation is nearing. While everybody is thinking about the future, your plans are aimlessly vague at best. One day, she brings your picture book to school and asks you to continue it, and not to forget your dreams from childhood days.