Main cast members refer to Taisuke, Tamamori, Hikaru, and Takizawa Miori.
First, magazine promotions.
6/15 - The Television - spread of main cast members
6/22 - TV Pia - main cast members on cover
6/22 - TV Life - main cast members on cover
6/24 - Only Star - main cast members on cover
6/18 - Ousama no Brunch - main cast members appear in VTR
There was also a bit of promotion on Asazuba this morning, so hopefully it'll pop up somewhere. There was promotion on HiruObi just now as well.
As well, there were newspapers articles about the drama, mainly in Sports Houchi and Daily Sports.
Since in the drama, A.N.JELL already has supposedly released six albums already, they revealed how the CD jackets for them look like. (This is before Miko - the girl Takizawa Miori plays join A.N.JELL.) You can see the jackets here.
For non-drama info, KisuMai has a new debut countdown serial on TV Guide starting 6/15. It's a weekly magazine. Also, the billboard in Shibuya is currently being changed to display KisuMai to promote for their tour. Those who are in Tokyo may want to drop by and check it out.