When he was first introduced, Rantaro seemed like a mysterious individual. Later it could be seen that he is a carefree and relaxed person. Despite his mysteriousness, he is described as one of the more ordinary students, with he himself stating that he can sometimes get a bit overwhelmed by the others' stranger personalities. Nevertheless, he is shown to have more patience than others with some eccentric students like Kokichi Oma and Miu Iruma.