Intending to challenge the Werebeasts, the siblings discover that it's hard to come with a strategy to defeat the latter, as all memories regarding the games are erased from their challengers, until Stephanie entrusts Sora a key left by the former king, leading to his secret research on how to outwit them.
The game Clamy challenged them to wasn't normal chess. Shiro is a chess master, but even she is helpless against Clami's assault. But when Shiro understands the real rules of the game, things begind to turn around. The battle to determine the king of Elukia, and all of humanity, finally reaches its end.