Kai and his fellow mates continue the search for Aichi. They follow up on the clue that Ren gave them, arriving at a Stonehenge-esque like location in Japan. Among the ancient ruins, Ishida fights Gaillard, and when that battle royale is over, another opponent appears, one who startles them all!

Kai and friends decide the only way they can get strong enough to defeat the Quatre Knights is through intensive training... but who is both strong enough, available, and willing to train them? Leon Souryu! So they travel to Leon`s isolated island, where an important lesson is waiting for Ishida.