Yozo’s use of morphine only provides him with a temporary sense of relief. The drug gives him a sense of elation at first, but nothing has actually changed about his life, so it’s unsurprising that he soon feels just as miserable as he did when he was still drinking. In fact, it’s arguable that his morphine use makes everything
worse, since he has essentially just taken on a new dependency—and one that is difficult and even dangerous to give up, at that. What’s more, living with this addiction further isolates him from the people around him, since he has to struggle with his cravings for morphine on his own. And though he starts a romantic affair with the pharmacist, he only does this as a way of getting more drugs, so it certainly doesn’t make him happy.