This is the nominate subspecies Sympetrum eroticum eroticum which occurs in northeast China, Japan and Korea.
This dragonfly is common and widespread throughout Japan.
It can be distinquished from other similar species by the hooked appendages at the end of its abdomen and the quite large hamulus (hook) at the beginning of its abdomen (clearly shown on the 1st and 4th photo).

1st, 2nd & 3rd photo: Maruyama Park, Kyoto, Japan, 1 October 2018
4th & 5th photo: Ritsurin Garden, Takamatsu, Kagawa Prefecture, Japan, 5 October 2018