Of course, Houki's final scene is in a bikini. Surprise!
The girl of Ichika's fantasy is probably Byakushiki... she was holding the Byakuya sword, clad in white armor. Shinonono Tabane (the one who put her sister's life at risk) did say Byakushiki has a will of its own, so in retrospect, her statement would support this interpretation.
Overall, all I really wanted to see was giant laser beams, swarming bullet barrages, and close sword combat. I got what I wanted. The weakest part was all the mushy stuff. Random girl (Byakushiki) appears and asks Ichika if he wants powah. Ichika responds "fight the powah!"
Then he comes to Houki. This is how it should have happened.
Ichika: Hey, I know today is your birthday, so...
Houki: What the hell are
you doing here!
Ichika: Um... I came to help...
Houki: Well, you're doing an awful job. While you're busy yapping away with me, our comrades are getting shot out of the sky!
Ichika: Err... but I have your ribbon here...
Houki: Do I look like I care about some ribbon right now? You know, maybe I would... if I weren't lying on a rock with my IS toasted!
Ichika: Y-You're so mean!!! WAAHHHH!!
Houki: Get out of my damn sight.