No, it is an evergreen azalea or Japanse azalea. Kinsai probably is not a hybrid but a cultivar of pure species Rhododendron indicum.
Most evergreen azaleas lose leaves in preparation of winter. Some lose all leaves, except the small leaves around the tips/flower buds.
Many satsuki lose a lot of leaves, the large leaves that are grown in spring just after flowering. So the first leaves on the new shoots, which are largest. These drop in autumn.
Some evergreen azaleas have been bred and selected to retain almost all leaves throughout winter. Many small-flowering European kurume are like that.
Older leaves eventually fall off. Leaves on azaleas generally have a lifetime of about a year.
That said, we can't tell you if your Kinsai is dropping leaves normally because of autumn. Or if it is dropping leaves for other reasons (ie dying).
Likely it is the former and many people get nervous when their azalea bonsai starts to drop leaves in autumn.
All the Kinsai bonsai in the autumn exhibition videos from Japan are now showing signs of dormancy. Probably because of a heated greenhouse to keep it lush green during the show.
They will look like this during winter:
皐月盆栽 小品 金采(Yahoo!オークション(旧ヤフオク!) )は21件の入札を集めて、2022/01/29 20:10に落札されました。
aucview.aucfan.com
Source: Yamaka Engei
Note, they look red rather than green, like described here:
www.bloomriver.com
www.bonsainut.com
