Love?
(Of course this is just done for fun! Don't take this too seriously!)

Eep!
Coupling: Lisa X Yusaku
Opinion: For shame! What about Tommy? Oh well, I guess a love triangle makes for more interesting ties between the characters.
Lisa and Yusaku being a couple would certainly bring a lot of humor and friction with Tommy. But Lisa seems quite immature for Yusaku. He doesn't share the same interest in her as she does on him. ^^;
From the radio drama, it is love at first sight for her (Well, physical attraction. Lisa: "Nice body!" lol!).
Coupling: Nagi X Yusaku
Opinion: No way I can see these two together. If they were, then it would probably be in some S&M situation with Nagi forcing poor Yusaku to do Nagi's bidding (Love slave??? @_@). I can't imagine them in any kind of fluffy romantic situation... it would just seem odd. Plus, Yusaku would seem too young for Nagi's taste (Oh, and the fact that she hates men. ^^;).
... ._.;
Hmmm...
Coupling: Yoko X Yusaku
Opinion: Hard to say if there is anything between these two that would possibly make them a couple. Though they both have some things in common: Both having to become leaders because the original leader has fallen victim to RED RUM, and both have fallen interest to female opponents (Lisa - Yusaku | Nagi - Yoko). There is also the fact that Yusaku is friends with Yoko's brother, Ken!
In the radio drama, Yusaku and Yoko seem to share a lot of dialogue together. They talk to each other as friends, but there is probably a bit of intimacy. ;)
I personally like to see them as a couple! They would look cute together! ^^
As far as I can tell, they make good friends and are probably too busy with their own problems to notice each other.
Coupling: Joe X Yusaku
Opinion: A popular yaoi fan coupling! o.o Of course these two don't share that kind of relationship in the game. In a sense, Yusaku doesn't want Joe to leave the SOUL CREW so he has some kind of attachment and adoration to Joe. Well, yaoi fans surely noted that, but to a much further extent. ^^;;;
What were they thinking???
Ack!
Coupling: Tommy X Yusaku
Opinion: Eh? Yes this pair has fallen victim to yaoi fans too!
Both are somewhat the same age and Tommy isn't bad looking either... But this obviously isn't going to work out. ^^;