Ittōsai Kunieda

is the grandfather of Aoi Kunieda and Kōta Kunieda.

Appearance
Ittosai is a fairly tall elderly man.

Return to Ishiyama High School Arc
When Aoi returns home from school with injuries, she receives first-aid treatment from Ittōsai. As he bandages her body, he learns about what had happened to her, becoming displeased when he learns that she refused to fight back, even though the ones who attacked her are former allies. Sometime later, several of the Red Tail girls arrive at the Kunieda residence while Ittōsai is still bandaging Aoi. He explains what Aoi had apparently told him and comments that she might listen to their reasoning instead. When he finishes up, he notices that some of the girls' male classmates have arrived, particularly Oga.

Powers & Abilities
Ittosai is the master of the Shingetsu style and can perform every technique it emplores. He taught Aoi and the Red Tails how to fight. He also showed no fear when facing off against Behemoth showing great combat prowess if not confidence in his skills.
 * Nadeshiko - A stone breaking technique which he taught to Oga and Aoi.
 * Kannagi - (Eighth Ceremony Sword drawing technique) Ittosai unsheaths and resheaths his sword quickly causing the area where his target is to be cut completely in half.

Tatsumi Oga
Mistaking Oga as a suitor for Aoi's love he immediately attacked Oga leading to a fight between the two. Despite winning, his opinion changed of Oga changed after seeing him take out some people trying to harass him. At the current moment, he approves of Oga as a prospective Grandson-in-Law.

Etymology

 * The name Ittōsai means "one sword, cut with a sword" (一刀) (ittō) and "religious purification/purification, Buddhist food, room, worship, avoid, alike" (斎) (sai).
 * Ittōsai's surname Kunieda means "country" (邦) (kuni) and "branch" (枝) (eda).