Appearance and Personality
Tadao is a calm man and a very responsible father. As a parent, he often makes sure that his daughters are doing their school work and checks on their progress. He has a common physique, light black hair and has brown eyes. He is the only one in the Hiiragi family who is right-handed.
Tadao is formally introduced in the series when he is checking Kagami and Tsukasa's test grades and tells Tsukasa to improve a little more. Most of the time Tadao plays minor roles, he is only seen when the Hiiragi's are watching television and when the cast is spending time in the Hiiragi Household. Tadao is also a volunteer at the local Takanomiya Shrine next to their house. He is seen working at the shrine during the New Year's festival in Let's Go to the Festival. In Base of the Sun, Tadao and Miki leave for a cruise, but they return due to a mistake on the date of their trip.
- Tadao is the first parent of a main character to appear in Lucky Star.
- Tadao is the tallest Lucky Star character at 185cm.
|Konata Izumi - Tsukasa Hiiragi - Miyuki Takara - Kagami Hiiragi - Ayano Minegishi - Misao Kusakabe - Yutaka Kobayakawa - Minami Iwasaki - Hiyori Tamura - Patricia Martin - List of Characters|
|Sōjirō Izumi - Kanata Izumi - Yui Narumi - Tadao Hiiragi - Miki Hiiragi - Matsuri Hiiragi - Inori Hiiragi - Yukari Takara - Honoka Iwasaki - Nanako Kuroi - Hikaru Sakuraba - Hinata Miyakawa - Hikage Miyakawa - Akira Kogami|
|Goldy - Cherry|
|Anime Only Characters|
|Minoru Shiraishi - Meito Anizawa - Daisuke Ono - Gotouza|
|Manga Only Characters|
|Kō Yasaka - Yamato Nagamori - Izumi Wakase - Fuyuki Amahara - Tamaki Yamanobe - Miku Busujima|