Here are the 2 clips from episodes #8 and #9 - the girls don't have much to do with the plot in these, they just show up and do a kind of blackout gag in the middle of the story. This time the gags feature Mika's (Tsukasa Minami's) F-cup rack.
The actresses that play the girls are:
"Mika" (the girl with the big bust) - Tsukasa Minami
http://asianscreens.com/tsukasa_minami2.asp
"Rina" (the tallest girl) -Shou Nishino
http://asianscreens.com/shou_nishino2.asp
Also there are some nice swimsuit photos of her here:
http://jappydolls.net/2010/03/shou-nishino-dgc-no819
"Maki" (the girl that wears her hair tied up in back) - Mei Itoya
http://asianscreens.com/mei_itoya2.asp