Toshio Zaizen (財前 敏夫 Zaizen Toshio) is the Communications Officer of the Antarctic Challenge Foundation's observation team. During expeditions, he usually stays at Showa Station to manage communications.
Toshio tends to act inappropriately around women in general, and was singled out for this during the welcome ceremony in episode 7.
He is also somewhat careless at times, such as when he caused a barbecue to inflame before the expedition teams were to leave for the inland station in their snowcats.
Toshio first appears at the informal Antarctic Challenge Foundation meetup at Kabukichō, Shinjuku, witnessing the commotion involving Kimari, Shirase and Hinata. At Fremantle, on the day before he boards the Penguin Manju Go, he invites fellow expeditioners Nobue Todoroki, Honami Yasumoto and Yume Sasaki for one last night out. Their conversation regarding their own doubts about the expedition is eavesdropped on by the four girls disguising themselves as spies.
In episode 9, Toshio confesses a crush, but calls it out on the wrong person (Shirase) and is forced to explain himself to Yumiko Samejima. He reveals that he was actually crushing on Gin Tōdō, the expedition leader, and heard that her friend was related to one of the girls. Because of this, the girls interview Gin. They report to Toshio and Yumiko that Gin's type is "like a cloud". The next day, Gin sheds tears for her lost friend, and Toshio witnesses this from behind.
In episode 11, Toshio informs the crew about an email that the station received from Hinata's old school. In the baseball game requested by the girls in the last episode, Toshio asks Gin out on the condition that he hits a home run. Toshio misses the ball and ends up hitting himself in the stomach.
- The name Toshio means "quick, clever, sharp" (敏) (toshi) and "man, husband" (夫) (o).
- Toshio's surname Zaizen means "goods, fortune, wealth, asset" (財) (zai) and "previous, before" (前) (zen).