What Color is Misaki? Natural Color?

It's little sister day at the cafe and Misaki discovers to her horror that she has no idea how to act like a little sister. Not willing to accept that she doesn't know how to do something she sets out to discover how exactly to act like a little sister. At the same Takumi is his usual unhelpful self. When another girl at school confesses her love for him, his answer is a surprise.