A Reason to Study is the fourteenth chapter of the Oushitsu Kyoushi Heine manga.
Heine gives Leonhard back his graded quizzes, all of which have very low marks. Leonhard was in denial at first, since he had worked hard, and Heine tries to cheer him up by saying that he had improved since the first test, since he now mastered the basics. Leonhard decides that the basics is all he needs to know and runs off, refusing to ever study again. While trying to find him, Heine bumps into Licht, who suggests that he should wait for him at lunch instead of chasing after him. Leonhard shows up as planned, and Heine drags him off to his room for lessons. He refuses to study without good reason, prompting Heine to tell him that he should study because his elders told him to and that it's all for his own good. This reminded Leonhard fearfully of his old tutors, but Heine retracts it and says that he doesn't know the 100 percent correct reason why he should study. He mentions that he himself only studied because it was the only way for him to survive. His father the king is so well-regarded because of all his hard work learning languages, history and many other subjects, and if Leonhard wanted to be king, then he should not see studying as something unnecessary. However, Leonhard is still hesistant because of his bad grades, but Heine tells him that his grades are not indicative of his future. He also tells him that he shouldn't expect to suddenly get good grades after years of not working hard, and that someone like him on the throne would probably be sent to the guillotine. This infuriates Leonhard, who decides to study hard and become a great king to prove him wrong. Heine silently thinks that he'll be waiting for that day to come.