Can someone explain the last frame of this chapter (71)? What's the common perception of people with B-type blood? Clearly, it's not good if Saaya tells Sakura not to mention to Ruka that she thinks she has B-type blood.
They're considered, to put it positively, free-spirits. Or rather egoistic, irresponsible, unpredictable, distractible and irreconcilable. Their positive traits are stuff like "passionate" and "optimistic".
For comparison, Type A is "responsible and patient" but "overly honest". Type 0 is "rational and amicable" but "critical". Notice how those have the sort of weaknesses you'd list about yourself during a job interview? There's blood-type based discirmination (bura-hara) which is primarily directed at B types.
It's certainly a coincidence that B types are a minority in Japan, but prevalent in China, Korea, South-East Asia and India, i.e. those ethnicities the japanese have racial superiority complexes about.