[Revised Itinerary]

Thank you everyone who gave feedback on my previous itinerary (https://www.reddit.com/r/JapanTravel/s/8swmXISqGV)

I have changed it quite a bit to spend less time travelling between Osaka and <destination>

Sep 21st day#1
Reaching KIX at 3:55pm.
Check-in to hotel in KYOTO

Sep 22nd day#2
Kyoto sightseeing , cover whatever possible among these:

    Southern:
        Fushimi inari taisha
        Daigoji temple

    Western:
        Arashiyama 
        Sagano scenic train
        Kokedera
        If time permits:
            Yoshiminedera temple

    Northern:
        Kinkaku-ji golden pavillion temple
        Kibune
        Kurama
        Ohara
        Takao
        If time permits:
            Enryakuji temple (Hieizan)
            Daitokuji
            Sanzenin

Sep 23rd day#3
Continue exploring Kyoto

Sep 24th day#4
Continue exploring Kyoto:

Central:
    Imperial palace
    Hoganji temple
    Nijo castle
    Sento palace
    Manga museum
    Aquarium??? Maybe. If its on the way

Eastern:
    Kiyomizudera
    Philosopher's path
    Higashiyama
    Kyoto national museum
    Gion
    Kenninji
    Hiking trail up to Shogunzuka mound
    Eikando temple

Sept 25th, day #5
Miyama (1hr 23min from Kyoto) on the way to Kyoto coast.

Kyoto coast (1hr 20min from Miyama)
    Amanohashidate
    Chionji temple monjido
    Hot sprint

Sep 26th day#6
Explore the remaining part pf Kyoto.
Explore Nara (56 min from Kyoto). Transfer to hotel in Osaka

Sep 27th day#7
Mount Koya (1hr 57min from Nara).
Kumano if I have extra time (1hr 29min from Koya).

Sep 28th day #8 and Sep29th day#9
Check-in at Osaka hotel in the morning (40min from Nara)

Kamikochi, Shirakawa-go, and Takayama 2 Days Bus Tour from Osaka:
        hot spring getaway at the renowned Okada Ryokan in Okuhida
        three-hour exploration of Kamikochi
        excursions to Shirakawa-go and Takayama.

If I come back early from Kamikochi on Sep29th day#8, explore Osaka.

Sep 30th day#10
Hiroshima and Miyajima (4 hours 9 mins from Osaka).
Osaka if I have time in the evening.

Oct 1st day#11
Hakone

Oct 2nd day#12
Flight back home at 10:55am