SPOILERS AHEAD:
Hanyuu's argument in the end, of doing it because of learning respect for her parents was a bit weak and too culture-showing-down-our-throats. But on the other hand whole thing holds water even better with argument of doing it to teach/remind her that she's now mortal. Maybe that's what we're supposed to infer? Either way, story pretty much works on all levels. I found it interesting how they chose to skip animating the brutality in this case, right decision given the context. Though it was a bit extreme, but that extremeness tries to carry the thematic message this time, realising that indirectly killing someone is still killing someone. But it might be a little too hardcore given the context. Coupled with respect for parents message, it's overall a bit stretched. It's just barely holds together.
