Great characterization here and, I agree, good rhythm to the story as a whole. Akihiko serves as an excellent pivot to characterize the others around.

The structure is also very good, bringing the story from Shinjiro to Ken, and then the final line. The closure is slight, at best, but that's all the story needs. Nothing's overplayed.

Nice work balancing the angst with touches of humor; it keeps it from feeling overbearing.

And again, wonderful characterization and dialogue.

Some crits:

"There was never [a] question of Shinji and Miki...they were already family anyway." I'd lose the "already" or the "anyway"; having both feels redundant.

"--last time--in his life uncertain" - very awkward phrasing/punctuation there

'"No, I'm not," he says, too harshly...unnerving she is.' I'd break that sentence into at least two.

In general, ease up some on hyphens and semi-colons. I overuse them too. Some are fine, but they're drawing attention to themselves.

This is the kind of rhythm I've been trying to achieve. Beautiful. I'm at a loss for words. Thank you.