And for those who don't want to play through the game (or don't have the game/don't have a console/don't have Japanese enabled OS/etc) BUT know some Japanese, you can always get this set of audio drama CDs (although getting 2 or more is already more expensive than buying the game itself):
http://www.cdjapan.co.jp/detailview.html?KEY=MACB-6001
http://www.cdjapan.co.jp/detailview.html?KEY=MACB-6002
http://www.cdjapan.co.jp/detailview.html?KEY=MACB-6003
http://www.cdjapan.co.jp/detailview.html?KEY=MACB-6004
http://www.cdjapan.co.jp/detailview.html?KEY=MACB-6005
These CDs retell each of the girls' story. It's not as detailed as the game, but it tells you all you need to know in 60 minutes.