Kannagi missed out on some good potential with Zange and her 'host'
Back when it was simply Nagi and Jin, I loved Kannagi. The introduction of the rest of the cast has damaged the show in my eyes. From the obvious and played-out contributions from Akiba and Takako, to the potentially good but largely ignored Daitetsu, most of what I'm seeing feels just off the mark. But the most missed potential has to reside in Zange.
This post contains some spoilers for Kannagi through 7 episodes. Nothing too major.
Is Zange really possessing a human named Hakua? 'Cause if so -- and it is so -- then Hakua needs to step up to the plate. Chew on this: wouldn't it be so much better if Zange and Hakua were at odds with what they wanted? I'm thinking of three possible scenarios here.
Scenario #1 has both of them liking Jin, but wanting to go about it in different ways. Let's keep Zange as the aggressive girl without any shame. With a shy Hakua, they unite to form the ultimate blue balls machine. Everytime Zange gets close, Hakua overrides her and pulls away. Jin then gets miserable being teased with all the mixed signals.
Option #2 has Zange in love with Jin, much to the chagrin of Hakua who hates him. Zange would jump all over Jin, only to have Hakua take over and beat the crap out of him. Everytime Zange would come onto Jin, he would immediately fear the worse. Fun would be had by all. Except for Jin... poor Jin.
#3 is the same as the last, except with the roles reversed. Zange is mean to Jin, but every so often he touches Hakua's heart and her warmth takes over... just long enough for Zange to build up enough rage to maul him. Typical tsundere, but we all love a good tsundere, don't we? The key difference here is all the potential infighting between Zange and Hakua.
All three scenarios have one common comedic element: Jin confused out of his wits. All three require Jin to be unaware of the real situation -- that the girl is possessed, literally. And all three I feel are better than the current status quo.

1) lelangir
Maybe Nagi should re-possess Jin, and then Zange possess Tsugumi so we get some odd sexual mishaps. Bodily musical chairs? I don't read the manga so I don't know what they're liable to do anyway.