Boku wa Tomodachi ga Sukunai S02E01 - I Think Something is Wrong with My Youth

Yozora and Rika manage to trick Sena into letting them style her hair into a heap, filling it with all sorts of oddities. The next day, Kodaka goes over to Sena's house to study for his exams, where he discovers her room is decorated with pictures of Yozora that she uses for 'grudge purposes'. Kodaka is asked by Pegasus to spend the night, where he expresses his worries that Sena might be getting bullied, to which Kodaka replies that he will protect her.