I loved some of the villain character development in last 100-120 chapters. Early on in the manga, I was afraid Kenichi would fall into the trap of "villain loses -> villain converts to the power of hugs, cookies and friendship". It's great occasionally (Shnpaku's Ragnarok recruits rule) but the author's done an even better job toning it down since. Let the villains be villains sometime, albeit with a human side.
The way Odin described Kenichi as "nothing but a big idiot" was perfectly in character for him as the bitter ex-friend. Boris being kind to the instructor, but continuing to follow his master's orders was nicely done. The King of Pincak Silat saving Kenichi's life, but being too proud to accept his pity. Even Shou, whatever his soft side, never directly betraying his master or mission as a Yomi disciple to defeat Kenichi. Rachel Stanley saving the school students from murder, but seeking Kenichi as her opponent. As long as the villains remain true to character (but not pure evil), I'll keep digging Kenichi. Although I don't mind the odd completely reformed Yomi member
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