Narimiya Hiroki [成宮寛貴] The first time I saw him was in Koukou kyoushi 2003 and I was really shocked because I knew I hated the character but I was, at the same time, mesmerized by him.
That's how I started watching dramas with Nari-kun in. His skill in actin is terrific, imho! He's become my fav actor... He can play different roles and I forgot he's Hirokun! Great, great actor.
Also... I found him totally crazy! I love his devilish smile soooooooo much!!! My fav chara of him was Shoei in Orange Days, but I also liked him as Takumi in Ima ai ni yukimasu.