Sendai's encouragement means a lot more to these three than it may initially seem. Beside the reason stated in the translation note, she is, as they are, also the nameship, and her 2nd remodel came four months after Jintsuu's, who received hers just a month after Naka's.
Fast forward to now — Only Nagara is missing her Kai Ni.
Kaga's Naval Base: Main tactical light cruisers' meetingKuma KaiNagara KaiTenryuu KaiBest regards kuma.Best regards kuma.Be patient. Polish oneself. —And wait.Ni... Ninja-senpai...!!!Even though we're Kai'd, we'll be on the front line next time kuma. Best regards kuma.I'm sure the moonlit night will shine upon you.Sendai was the last of the Sendai-class cruisers to receive Kai Ni, after Naka and Jintsuu.