The pine trees and Kirishima azalea that grow in the garden before the Kobuntei house, together with the white enkianthus flower bushes, shine brightly.
The light of each tree is autonomous, shining brightly, then fading.

When people approach and stand still near the trees, the light changes color, and a tone specific to that color resonates out. The light of the tree radiates outward and is transmitted to the surrounding trees one by one, as the sound is continuously emitted. If a wave of light comes from the other side, it signifies the presence of people there. People gain a heightened sense of awareness of the existence of other people in the same space.

Among the azaleas is the Kirishima azalea, which is about 300 years old and was planted in the Edo period. It is believed to have been donated by the Satsuma Domain, and it is designated as a near-threatened species on Mt. Kirishima, its place of origin. The number of old trees is small nationwide. Kairakuen Garden was opened in the late Edo period (1842), which means that the azaleas were planted when they were already 80 years old.