Main Anime Characters:
Aine - Manager, Publicist and Sister to Atsuro - Bubbly, Caring, and Competent

Sakuya - Lead Singer - Arrogant, Obnoxious, Driven, Moody and very Talented

Yuki- Lead Guitar- Responsible, Sensible, Intelligent, Diplomatic - and
Seductive

Santa - Drummer - Hot tempered, Wild, Optomistic

Towa - Base Guitar - Quiet, Serious, Devoted to his Music, Sensual -
crossdresser

Atsuro - 2nd Guitar - Bubbly, Eager, Adorable and Insecure

Story:
Unlike the Manga - thank goodness - that focus on Aine's love life and seems to make her the incompetant Anime Heroine courted by a whole J-Pop band of beautiful guys - talk about wishful thinking.  Kaiken Phrase focuses in the first 16 episodes on the creation of a band and their struggles to make it to the top.

The Story starts out with Santa  and Yuki leaving their old band Climb
because Yuki's girlfriend the lead singer is caught cheating on him with the
base player.  Eager to start another band they decide they want Towa.  He's
interested but doesn't want to leave his current band - unless they have more
to work with - like a lead singer.  Eventually Santa and Yuki learn about
Sakuya and try to get him to join.   He is a singer piano player in a bar and
a gigalo and is uninterest.  Yuki however persists and with his understated
style and the help of outside events convinces Sakuya to listen to their
music and visit a live bar where hopeful bands play.  There Santa and Yuki
play on Sakuya's ego and get him to sing a song with them.  Towa sitting in
the audience and Artsuro  can't resist getting up and joining in.  Artsuro is
unhappy with his band Lucy Lee and is eager to join a band where the music up lifts his spirit.  Towa left his band because they were more interested in
appearance than music.   And Lucifer is born.

That makes it sound simple but its not.  Sakuya still requires convincing and
even after he joins still needs to deal with his flaws like his life a gigalo
and his attitude.  Yuki - was a No performer and is torn between the
traditions of his house, his father and the Band.  Artsuro - has a similar
problem but his father wants him to go to college so that he can have a good
life.  Santa is still struggling with his feelings of betrayal and Towa -
well I have hopes for Towa - but right now he is mysterious all we know is he
ran away from home and never looked back.

On a side note if you like Hetro as a side story Aine is actually the kind of
character I can see some one falling in love with.  She has all the anime
heroine +s (ie a good heart) and none of there minuses

Potential Slash Couples:
Artsuro was born to be a Uke - there is no getting around it - I can't see
him topping anyone.  He admits in the anime to be in *love* {whether it is
just admiration or Luv is uncertain} with Sakuya.   He often blushes adorably when talking to the brooding lead singer and he is always bringing him food his sister made to get in Sakuya's good graces.  Sakuya refers to him to Aine as your cute younger brother - even though I think Artsuro is the elder.

Artsuro also lives for a time in Towa's house and obviously looks up to him
as a mentor - what he would like to be.  While in Towa's house - Towa makes a small pass at him and then says he's just joking - but they both blush and Towa laughs awkardly.

Artsuro looks so feminine after he dyes his hair red that - even though they
are less likely - Towa and Yuki would be great topping him

Sakuya is sort of a switch hitter, I can see him topping any of the guys and
the only one I can see topping  him is Yuki - but only if he seduced him.  I
think Santa would like to -but I suspect Sakuya would turn the tables.  At
one point in the anime Yuki says Santa love him (Sakuya) the most of all of us.  No one disagrees that they love Sakuya.  I can see Santa having a real love hate relationship with his lead singer.  Also  Sakuya writes Datenshi Blue - a highly suggestive song for Lucifer to sing.  The band members think it is a love song to Lucifer (them as the band)

Towa - probably the uke with every one but Artsuro - beautiful Mysterious,
seductive and a cross dresser -chuckle - I don't think more reasons are needed

Santa -I could see him Topping Towa and Artsuro, surprising him self by
bottoming with Sakuya - but with Yuki I am not sure - they are very close -
trust each other a lot and know eachothers hearts - I think they would be an
equal pairing

Yuki - Top to almost every one - unless Sakuya organized the tables being
turned yum.  Lives for awhile with Towa and has the most influence on Sakuya and Santa

Truthfully - mix and match the combinations anyway you like and with this
anime you can't go wrong