|Full Name: Isshuu Kasumi
|Ranger Designation: Kuwaga Raiger
|Weapons: Stag Breaker, Ikazuti Maru
|Gear: Gourai Changer, Bari Thunder
|Karakuri Machine: Gorai Stag
|He is Ikkou's younger brother. He had a strong dislike for the Hurricanger. He followed everything his big brother says. He is a bit feisty. In Episode 17, his brother tried to kill him when they were forced to fight because of destiny and he refused to. He said, "My brother did everything. He even threw away his humanity. And his little brother... me... he's trying to kill." He explained it all to the Hurricangers about his father Ikki Kasumi pushing them to fight all their lives. Isshuu joined forces with the Hurricanger in Episode 17. Isshuu did occasionally hang out with the Hurricanger. In episode 26, Cyupid threw an arrow on a teen idol Katsuya and Isshuu making them fall in love with Nanami when they saw her first. Even though they were in a spell, Isshuu really is in love with Nanami! He is too shy to express it. Isshuu was always feeling torn. He wanted to do the right thing, what he feels in his heart but he also wants to please his brother. For example in episode 31, Ikkou wanted to die with 'dignity' and not be helped. Isshuu knew he should get help and told the Hurricanger but he knew that is against Ikkou's wishes. Yousuke ended up slapping Isshuu back to his senses.
In episode 38, Tenraisempujin simply had too much power. Oboro looked at schematics for the two combinations, she said that it could be Goraijin causing the problem. Oboro wanted to alter the Goraijin. Isshu is not happy about this at all. Isshu loses his hold on his temper and grabs Oboro, shaking her. Nanami and Kouta manage to pull him away. He was quite upset and said, "Is all of Ikazuchi Way to be lost?" Mugensai told the Hurricanger that inside Isshu sleeps the spirit of his father, Ikki Kasumi. "But he resents his father!" Yousuke protested. Oboro said understandably that resenting your parent doesn't free you of their influence. Their thoughts dwelled on Isshu about protecting and keeping in the way of Ikazuchi. Isshuu at the end resolved his issues to save the world. When the Hurricanger thought the Gouraiger had died in an explosion involving Saandaru, Nanami yelled out for Isshuu. He lived in Spain with Nanami in Abaranger VS Hurricanger and had two tickets to an bullfight. Apparently, still mesmerized by cows.