Z arc

After the festival, Ruka studies for the final exams along wih Class B. After linchou's Alice is stolen and Hotaru is injured by Z, Ruka, Mikan, Natsume, Tono, and Tsubasa sneak into the

Ruka and Natsume as 15-year-olds~

 high school section to use the rumored Warphole to go Z's hideout. Ruka, Mikan, and Natsume must disguise themselves as high schoolers using Gulliver's Candy. He is flustered after seeing Mikan as a high schooler, and even though he is older inside, he is still a ten year old. Not long after arriving in the high school section, he and Mikan become trapped in anti-gravity chamber- they accidentely went into it after their Gulliver's Candy wore off. Ruka and Mikan are both rescued by Tsubasa's Alice. Ruka along with Mikan, Tsubasa, and Mikan use the Keyhole (acutally called Keyhole and not Warphole) after proving themselves to be serious about going to Z's hideout to president Sakurano and vice president Subaru.

They are transported to a wooded mountain with dangerous traps surrounding everywhere. Ruka and Penguin were about to be turned into to stone by a tree, if Mikan didn't nullify the attack using her Alice powered up by Tono's Amplification Alice. Ruka's Animal Pheromone Alice becomes a very valuable source of information for the group, with him being tasked with asking the animals which warphole Z used. Ruka and Mikan spend some time alone admiring the view of the lake reflecting the moon, the night before using the warphole to transport to Z's location. He promises Mikan that one day he will give Mikan his Alice stone and she agrees to give him hers (Mikan didn't know about the exchanging of Alice stones meaning soul-mates). Ruka is overcome with guilt when he realizes that Natsume also has the same feelings for Mikan and leaves her to find Natsume, so he could see the view of the lake too. He later eates some grapes that Penguin brought which turns out to have alcohol in them. This causes him to hug Mikan, but is peeled away by Natsume and falls asleep. Later on, when he, Natsume, and Tsubasa was fighting the Z's, he got affected by the Z's boss alice from protecting Tsubasa. He is healed by licking Z' boss' blood off a knife, given by Yuka. Then, the ceiling collapses and they flee. Despite the apparent life-threatening circumstances of the escape, they all return safely to the academy.