First there is a character coded name "Jin" (portrayed by Eriku Yoza), who transforms into UltraSeven X. He is a top DEUS agent. However, he loses his memory. As expected, his past is shrouded in mystery. Also, there is his relationship with the mysterious Elea. As the story develops, the truth starts to emerge...
Then there is the mysterious Elea (portrayed by Saki Kagami), who gives Jin the glass to transform and is often nearby. She is the key to all the mystery in the story, such as Jin's past.
Then there are two other DEUS agents, Agent K (portrayed by Tomohito Wakizaki) and Agent S (portrayed by Anri Ban). I don't know much about them.
(Yeah, the (bare) character profile is a complete rehash from the official site, whose look I do like.)