If you can believe the rumors, Haruma got the kind of "star" role in this because Takaki Yuya is lacking a talent for acting and Miura is the superior actor...
I've read on Japanese Tabloids that the script was changed and a lot of lines and scenes were shifted to focus on Ren instead of Yamato.
So... lucky?
XD
(Johnny's Pimping avoided...kind of)
I must that that even though Gokusen 3 was repetitive when compared with the other seasons, it still had its' own charm due to the choice of cast members and well, after having watched episode 11 I can kind of guess what's going to be put in the Gokusen 3 movie.
Dunno if you all heard it but there's a Gokusen 3 movie in the planning and shooting is said to be started towards the end of this year or beginning of next year (since it will definitely have a graduation part in it, I guess since it wasn't in the actual series).