Bipolar Disorder is emotional dysregulation while BPD is mostly an unstable identity. People with BPD constantly have shifting, inconsistent ideas of who they are. Noa exhibits this by her constant doubts about her approach to things, even her "career-mode" gets put to question due to external influences like Rihito. This extends to relationships via idealization/ devaluation where Noa is either praising Rihito as a super- best friend or not doing enough as a friend; it never occurs to her that people are complicated and they're not always black and white).
So yeah, it is the dreaded BPD. Makes for good comedy, but IRL avoid like the plague.