|Japanese name:||泉 そうじろう|
Sōjirō is very thin, and has unshaven facial hair, he has a mole under his left eye which his daughter inherited and has thick eyebrows. Additionally, he is allergic to pollen and when he decided to wear goggles and masks as protection from it, Konata sighed that, "Now you look weirder as well". She also frequently reminds him, "Please don't do anything as to be taken away by the cops". Also, he often forgets to lock the door when he is using the toilet, which has left Yutaka with a tremendous shock.
Sōjirō holds a deep love for his wife, Kanata Izumi, who passed away many years before. When Konata asks why Kanata chose to be with Sōjirō (largely as a joke at his erotic personality's expense), Sōjirō points out that he and his wife simply looked past outwards appearances: Kanata loved Sōjirō despite his otaku tendencies, and Sōjirō obviously did not mind that Kanata had an unusual physique and did not share his hobbies.