Kida is attractive and confident. But being a dark-haired female character, obviously, that combination isn't allowed in fiction. So there's no doubt she has crippling psychological problems and needs Kotoko to save her from her life.
Seems like just another boring yuri drama that will follow the same misogynist arcs and feature the same misogynist personalities as they all do.
But if that isn't the case and Kida and Kotoko are exactly as they seem at first glance - you know... as is the case anytime the story is about a confident blonde and a shy brunette - that would actually be really interesting and unusual.