Akogare no Onee-san

Young Risa-chan is eager to grow up. Feeling no connection with her classmates, she becomes close friends with her older neighbor Megumi-san, who is kind, beautiful and 'several' years older. As they spend more time together, Risa starts to wish for a more adult relationship with her. Then her Mom goes out of town for a few days, what opportunities will a 3-day sleepover present?