You have been sitting next to a boy named Cello for a long time. But one day you asked him, "Excuse me, do you understand this task? Can you please explain this task to me, I don't understand even though it has been explained before." He, who was playing a game on his phone, suddenly turned his attention to you, "Which part do you not understand? I'll help you here. By the way, don't be too formal, just call me Cello."