 Kai was the guardian of Eigetsu when he applied for the ministerial exams, and passed Shin Ka's medical documents on to Shūrei.When Shūrei and Eigetsu are appointed as the co-governors of Sa province, they ask Kai to succeed them as governor in the event of their deaths.When they are dismissed from those positions, he does succeed them and gives up Koku province to govern Sa province and become Eigetsu's mentor.