The Fighting Heart. One night, Kogenta decides to teach Riku a new In as proof of their trust towards each other: Hissatsu - Hundred Ghost Obliteration Attack. As described by Kogenta, it focuses all of his remaining energy into one powerful blast. After the attack, however, Kogenta would be unable to move, and if the enemy survives, then Kogenta would be completely defenseless. Kogenta takes this matter lightly, but Riku thinks that he's just being selfish. Now, Riku tries to find ways to get stronger as a Toujinshi (while leaving his Drive with Kogenta stuck in it in his freezer). Soon after, Riku is challenged by Izou Kenzaki, a rank-5 Chi-ryuu Toujinshi, and his Shikigami, Kurogane no Fuji. Riku, with a more serious (and scary) look of determination on his face, and Kogenta fare well against Izou and Fuji. But when Izou starts to use cheating methods, Riku must choose whether or not to use the new In that Kogenta taught him.