In particular, it will depict the battle of Kenshin Himura and Makoto Shishio and will be told from the point of view of the Oniwabanshū ninja Misao Makimachi.
What.

This makes me wary, seeing as how Misao was never present in the infernal arena in either the manga or original TV anime.

Shishio battle was a pretty messy affair already, considering all the characters involved; no need to drag more in.