Spiral, Vol. 4: The Bonds of Reasoning — Kyo Shirodaira

When Hiyono turns the tables on Rio and Kousuke and demands a rematch for Ayumu, she ends up getting kidnapped! However, it looks like there'll be a rematch after all. In exchange for his trusty information dealer, Ayumu must hand over Hiyono's hard evidence against the Blade Children...in one of Rio's devilish games! Will Ayumu's pride be his downfall?