Truth be told, their absence has less to do with grief than with the personalities of those left behind. Mother had supported Father's political career but she has no interest in high society herself, and his brothers would only embarrass the family. Yaichirou is the only one left who cares about their reputation.

"It was somewhat difficult considering the close quarters." Read: he got maybe fifteen minutes of sleep and woke up with pins and needles all over. Airline seating just isn't build with tall people in mind. "I hope that you fared better."

He's operating on autopilot while he searches for a polite way to ask the burning question: why isn't Kou back home, learning the family business? He's been out of touch, but if there had been an upheaval serious enough to make them question Kou as their heir, he definitely would have heard.