Yakumo "Cloud" Katou (加藤 "クラウド" 八雲 Katō "Kuraudo" Yakumo?) is AoNinger (アオニンジャー Ao Ninjā?, Blue Ninja), who is known as The Cool Ninja (おちついた忍者 Ochitsuita Ninja?)[1], the Blue Ranger of the Ninningers. He is mostly nicknamed as Yakkun (やっくん?) by Fuuka and Nagi.