To fight is different from violence - S1.E5

Sawada finds Yankumi's lost phone and sets out to return it. In doing so, he ends up in a house filled with Yakuza and learns the truth about Yankumi's family from her grandfather. Meanwhile, the teachers are on the lookout for a violent gang of young men who have been attacking pedestrians, and Kumai has become smitten with a girl from another school, who he learns already has a boyfriend. Later that day, Kumai learns that the girl's boyfriend is the gang's next target. Concerned for her safety, Kumai rushes after them. While he is watching, the gang members corner the girl and her boyfriend, and the boyfriend runs off. What will Kumai do?