AC - NH TYO Codeshare
 

So just checking flights from TYO to YVR and AC marketed flights are only available on AC metal - NH flights are available on both NH metal and AC Codeshare. I'd prefer the later departure from HND on NH but not at the expense of no AQD!

Why would reciprocal arrangements not be the same on both airlines?

remove. error

AC does codeshare on the YVR-HND flight operated by NH:

AC6249 YVR-HND (operated by NH)
AC6248 HND-YVR (operated by NH)

Yeah. That flight has been there for a long time.

When I clicked this thread, I thought it was going to be about the difference in price for J.

OK sorry about that - I see it now in EF and while technically it shows availability on and around June 1, cannot fare it on ITA and AC.com doesn't show it as an option either.