Aoi Yu [蒼井優] Don't let her baby face fool you! Aoi Yuu has versatility. From the neurotic, anorexic patient Miki in Welcome to the Quiet Room to the sweet and bubbly Osen, Aoi Yuu plays 'em all, and she plays 'em well. Definitely my favorite Japanese actress. She tends to stick to movies as exposed to dramas, but I'm not complaining about that.
Eita [瑛太] Unassuming but extremely prolific--he's always popping up and dramas and movies when I least expect him. Eita is always a joy to watch, and isn't afraid to give him characters an extra umph. I don't know 'bout you guys, but I find his boy-next-door looks quite charming ^^
Kase Ryo [加瀬亮] Why so few votes for Kase Ryo? He is an incredibly talented actor whose charm permeates the screen. His characters always leave a lasting impression.
Ninomiya Kazunari [二宮和也] I walked into Letters from Iwo Jima expecting to see a fine performance from Watanabe Ken (and I did), but I walked out completely won over by Ninomiya Kazunari. At that time, I had no idea who Arashi was, and I had no idea Nino was so well known in Japan. So, when I searched up Ninomiya Kazunari on YouTube, I was quite surprised to find him in rainbows and a bowler hat in the Kitto Daijoubu PV. What a difference from the solemn and introspective Saigo! Nevertheless, I find Nino-chan a wonderfully talented actor (and with time, I grew to love him as an idol too). He consistently delivers, and unlike most Johnny's, he is able to turn off the idol mode and really assume the identity of the character he's playing, as demonstrated in Haikei Chichiue-sama and the movie Ao no Honou. A true talent, a gem in JE :)