Booking JAL domestic flights
 

I can see availability for international flights originating from Japan for the year ahead, however the domestic flights only go up to August so far

I'd only use Avios on domestic JAL flights if I had a mountain of Avios - look up the JAL Japan Explorer Pass - flights are super cheap for non-Jap residents. These fares can also be upgraded to Business for just JPY1,000 (albeit on a standby basis at check-in)

Remember that domestic "business class" (called "Class J") on JL) doesn't give you any food or extra drinks. It's just a bit better seat but you could still end up in a middle seat, especially when booking at the last minute e.g. standby.

I think that 60 days is changing, see post 89 https://www.flyertalk.com/forum/brit...-awards-6.html

I had been looking for domestic flights for 2020. Lots of availability would show on ba.com but the transaction would never complete. So I assume that the 60-day rule is still applying.

For JAL pure/standalone domestic flight by avios, CURRENTLY, 60days advance.
Several months ago, it was 62 days advance by avios.

Because JAL own JMB member can book 2 months advance (NOTE, 2 months aren't 60days/61days/62day see below).
As JAL JMB member you can book
31 Aug flight at 30 Jun (62 days advance)
31 Jul flight at 31 May (61 days advance)
31 Mar flight at 31 Jan (59 days advance).

Previously, Avios redemption can book 62 days advance. IMHO, by some complaint, it has been changed to 60 days advance now.
Of course, a few years ago, Avios redemption can book 330 days advance even a pure domestic flight.

About redemption combining with an international flight, JAL provides award in 360 days advance.
So, 353/354/355 days limit is BA booking system limitation.
I find HIJ-HND-LHR award on 30Jun2020 on today(12Jul2019 JST).

BTW, On 12 September 2019, JAL domestic flight can be book 330 days advance. Yes, drastic change.
So, probably, domestic only flight award situation will change.

About class J/First class same day standby based upgrade,
you can upgrade from ANY TICKET (including redemption tickets, group fare, etc.) by paying 1000/8000 JPY respectively.

Strictly speaking, class J has two more soft drink options over economy class.
One is vegetable mix juice, and one is special green tea.

You'll get the upgraded into cabin's TP usually too. :)

If you are flying on a route which has it, JAL's domestic first class is also worth considering. An upgrade starts at 4000 yen. Whereas their business class is basically just a nicer seat, the first class offering includes an even nicer seat with food and alcohol.