@Demomanowar
1. Hime could have sneaked away or just be off the clock.
2. Kokoro could be playing another part in this investigation or just be doing normal cop stuff. Pretty sure Hime joined Chilo and Nada in the special division while Kokoro stayed with the normal cops.
3. Oscar is a normal police officer so no reason to have him take part in a supernatural case, and if they did get him involved everyone knows his feeling for Flora and there is a good chance he would do something reckless and ruin everything.
4. Just like Oscar if they inform Flora of whats happening the case could be ruined and they would have to start back at step one. As for telling Creepy, it wouldn't be uncommon for him to protect her so telling him whats happening would just nudge him in the right direction and not seem too sus.
Sorry about the point form answer, it's just easier to lay my thoughts out like this.