One who doesn't have willpower:

Episode 5 - Kuroneko

Quite a good episode. Action wise this was perhaps silence between storms, but it explained some things, mainly Jin's motives and much of the backgrounds of the current events. Still no idea what's the role Sana is playing in the bigger picture, though. But perhaps she's genetically engineered.

The next episode agains seems to return to hard action, though. Too bad it won't air before 13th of September, according to the preview.