Sanrio Boys - Season 1 Episode 3 My Sister Blue

Finally able to admit his love of Pompompurin, Kouta feels relieved and has made friends with Yuu and Shunsuke. It turns out that while Yuu may seem flashy and carefree, he's actually a pretty responsible older brother taking care of his younger sister, Yuri. However, Yuu's life isn't quite as easy as it seems. While he does his best to take care of the house and sister while his parents work, Yuri seems to be going through her rebellious phase and nothing Yuu does seems to be good enough. One day, when visiting Yuu while he's sick, Kouta and Shunsuke accidentally end up in the middle of a fight between Yuu and Yuri. Fed up with his sister's cruel words, Yuu storms out of the apartment forcing Kouta and Shunsuke to run after their friend to make sure he's okay.