Fukuzawa is a serious, collected and reserved man. He tends to give dry answers without any expression, but it doesn't mean that he isn't happy, sad or angry sometimes. He is very calm and nice, especially with Ranpo Edogawa, who he sees as his son. Although Fukuzawa is emotionally reserved and impassive, he can display a sense of humor. despite everything, he is a loving man (and a little more with Ranpo) and educated.