His Relationships with:
Kurei: Raiha is totally loyal to Kurei. He is, in a way, Kurei's best friend, except that at that time Kurei hadn't realised that yet. He will do anything for him, even risk his life to do whatever Kurei tells him to. Sort of like Recca's attitude towards Yanagi, if you know what I mean. (The "I'll do anything to protect my lord" bit) I believe he is Kurei's right-hand man, as he is always seen near Kurei. During the Dark Martial Combat, he was watching Hokage's fights with Kurei on the screen in his mansion. He knows about Kurei's sad past and will not stand to hear anyone label Kurei as "cold-hearted".
Neon: Seems to be really good friends with Neon, since they are always seen hanging around together and trading comments on the fighters in the Dark Martial Combat. But they are definitely NOT romantically interested in each other. Neon only has eyes for Kurei, and Raiha is only interested in Fuuko. ^_^
Fuuko: Tsk, tsk, need I really say? He likes her ALOT, even though they are enemies, so to speak. However, this isn't too clear in the anime, although it is more defined in the manga. I'm not sure if Fuuko knows about his love for her, though.
Kaoru: Raiha seems to be Kaoru's mentor, and he doesn't wish to see any harm come to Kaoru. I mean, he DID warn Kaoru against going to the Dark Martial Combat. However, since Kaoru has "betrayed" Uruha, he can't really do anything about Kurei's wishes to kill that "traitor"
Kouran Mori: Urgh! Do I even HAVE to mention this disgusting piece of slime? Raiha treats him like an employer, and will do whatever Kouran wishes, but that doesn't mean he likes it!