13 days to Northern Kyushu/Osaka

Hi everyone

I visited Northern Kyushu in Nov 2018 for 6 days and could not get enough. I visited Karatsu and Nagasaki, however both were day-trips.

I'm thinking of visiting Northern Kyushu again, and cutting down the number of days in Fukuoka. I would really appreciate if you can help me have a look at my itinerary.

14-15 Nov - Fukuoka (Dazaifu is a must-go this time)
16-17 Nov - Karatsu (Karatsu, Yobuko market, Nanatsu-gama) - should I rent a car?
18-19 Nov - Nagasaki (Oura Church, Mt Inasa. I have already visited the Peace Park, Chinatown and Meganebashi)
20 Nov - Fukuoka (a sort of stopover before going to Osaka the next day)
21-25 Nov - Osaka (inclusive of day-trip to Amanohashidate in Kyoto)
My husband intends to eat his way around Osaka so I hope the 4 days we are there would be sufficient.

Should I squeeze in Kumamoto as a day trip?
If yes, should I visit Kumamoto after Karatsu, then to Nagasaki?

Thank in advance for any valuable advise that you can provide.

RE: Kumamoto. I am not sure what you wanted to see in Kumamoto, with its castle, the number 1 attraction there, still being out of comission. If you want to see a castle, why not stop in Himeji on the way to Osaka. Himeji castle is considered the best castle in Japan (and I agree with that assessment).
https://www.japan-guide.com/e/e3500.html

If you are up for renting a car, then you have a lot more freedom and can see a far wider variety of places. You mentioned some things that you saw before. For Fukuoka, you could see the Nanzoin Temple just outside of town and inside there is Tochoji, Japan's biggest wooden carved Buddha (about 10m high and 30 tons).
http://www.thejapanfaq.com/fukpic.html
http://bit.ly/1KAm8cU

Dazaifu is fine; the Tenmangu shrine is the biggest draw (don't miss the garden next to it) and if you want, the Asian Museum in one of the big ones of Japan. But you will likely have time for more - you could fit in Yanagawa with its nice canal boat rides.
Karatsu is not bad either; the quaint castle is nice, but if you have a car and the weather is good, driving to the top of Kagamiyama is wonderful. I did the 26 hairpin turns on my motorcycle and it was a lot of fun. The view is superb from the top.
For Nagasaki, one of the best sights is along the way - visit the Yutoku Inari Shrine. It is an undersung jewel and very beautiful.
https://youtu.be/2UU_1Aip_l4

Nagasaki you could see in a day if you have some of it already under your belt. There is also the Koshibyo Confuscius shrine, Dejima, and Glover Garden. Mt Inasa is best at sunset to watch the city day turn into night.
http://bit.ly/2ob4u8i
For Kumamoto, as mentioned above the castle is still closed. But if driving, you could see Aso. Check first to see if the crater area is open and if so, you are in luck. Nearby there is also the beautiful Nabegataki waterfall and the Daikanbo Lookout is killer.
http://bit.ly/2HopvoC

I do concur with the above - if you want to see a castle, then see Himeji Castle (and don't miss the Kokoen Garden nearby).
https://goo.gl/65ZtRi

You should have no problem finding good food in Osaka.

You don't need to rent a car unless you expand your itinerary.

14-15 Nov - Fukuoka (Dazaifu is a must-go this time)
This is easily accessed by train and should only be half a day.
You might consider a canal boat ride in Yanagawa or see the reconstructed Yayoi city at Yoshinogari.
https://www.japan-guide.com/community/mfedley/report-2676
https://www.japan-guide.com/e/e8325.html

Nanzoin with its large bronze Buddha is easily accessed by train.

16-17 Nov - Karatsu (Karatsu, Yobuko market, Nanatsu-gama) - should I rent a car?

If you rent a car, getting to places like Kagamiyama east of town, Nagoya Castle ruins/museums/battle camps NW of town on the Hadomisaki, the terraced rice paddy at Hamanoura, and the Nanatsugama Sea Caves would be accessible. If you're just spending the day in Karatsu, a taxi would be easier if you didn't want to walk.
https://www.japan-guide.com/e/e8375.html

18-19 Nov - Nagasaki (Oura Church, Mt Inasa. I have already visited the Peace Park, Chinatown and Meganebashi)
Even adding Glover Gardens and Dejima wouldn't take a lot more time to this schedule. You could add a trip to Hashima (Gunkanjima) or do as the Japanese do and see an earthquake-proof Dutch town recreation at Huis ten Bosch.
https://www.japan-guide.com/e/e4414.html
https://www.japan-guide.com/e/e4477.html

20 Nov - Fukuoka (a sort of stopover before going to Osaka the next day)
Why not stop at someplace in the middle beyond Fukuoka such as Hiroshima or Onomichi (Shimanami Kaido). Either one is a couple of hours on the shinkansen beyond Fukuoka.
https://www.japan-guide.com/e/e3478.html

21-25 Nov - Osaka (inclusive of day-trip to Amanohashidate in Kyoto)
That's a lot of time just for eating street food.

If you have a JR Pass, quick shinkansen day trips would be easy. You could get to Kumamoto City, take the tram to the castle (shiakusho-mae stop), walk around the outside of the castle to see the damage (not all is damaged), stop in the Craft Center on the north side, take the tram down to Suizenji, and get back to Hakata Station all in about 5 hours. It takes about 50 minutes from Hakata to Kumamoto. Based in Osaka, you could take a day trip to Kyoto, Nagoya, Kobe, or Himeji without wasting too much time on travel. It takes about 45 minutes from Osaka to Himeji using the shinkansen.

@9shoe
I read somewhere that the view from Daikanbo is breathtaking hence I am a bit tempted to make a visit to Kumamoto.

@Ken
Thanks so much for the suggested places. I could not decide what places to visit aside from those I mentioned in my post. Now that I know that I can probably fit in more, I will definitely add them in.

@Anaguma
I tend to play safe by staying at least 2 nights in one location in case I could not visit intended spots for whatever reason. I find overnight stays a bit stressful.

*cough*I'm actually a huge fan of Yuri On Ice hence it's actually an anime pilgrimage of sorts. The day trip I did in Nov 2018 was not enough hence this repeat visit. I'd probably keep day one for YOI locations including Kagamiyama, and the day 2 for Yobuko Market, Nagoya Castle ruins, Nanatsugama Sea Caves and Hamanoura rice terrace. Is my day 2 plan doable in one day if we rent a car?

The reason why I'm going back to Fukuoka for one day on 20 Nov is because I intend to leave my luggage with the same hotel I stayed in the first 2 days (have yet to arrange but hope they are flexible). I shudder at the thought of lugging two 28" luggages across Northern Kyushu.

One more question, which I forgot, may I know when should I start booking the car rental?

Once again, thank you so much to everyone, for your advice. I really, really appreciate it. I will tweak the last leg in Osaka, probably by adding more day trips as suggested.