Naruto learns this the hard way after using his shadow clones, Naruto quickly collapses from the pain caused by the seal. Naruto is later taken captive by Maroi who is working for Mui. When Naruto is brought to a lab, Mui realises that the Naruto taken was a clone. While the real Naruto was hiding, he used the chance to escape. But the pain from the seal made him pass out.
After being caught, he was taken into solitary confinement. When in solitary confinement, he hears a mysterious voice say that if he can defeat Mui, then the seal will disappear. Naruto then after being released, attacks Mui. But the seal causes Naruto to collapse, and he is taken back into solitary confinement. During the fight, Mui questions Naruto's devotion to his home, wondering why he bothered being loyal. When Naruto is released, he is looked up to by the rest of the prisoners. Naruto later attempts to escape again, by knocking out one of the guards and taking his clothes, when his shadow clone fools everyone. As he is able to get to the edge of the island where Ryƫzetsu tells him to stop, Naruto refuses to listen, and he jumps into the whirlpool.
He nearly drowns, but Ryƫzetsu saves him.
Naruto thought she was a boy, but later sees that she is a girl, and that it is her mission to kill Mui and stop the Box of Ultimate Bliss. She reveals that Mui even sacrificed his son, Muku, to the box and also that Mui set Naruto up. She asks for Naruto's help to destroy the box. In the next day, Naruto challenges Mui again, but is defeated and taken to solitary confinement.