S. japonicus has a relatively limited flowering period; a single flower has a blooming period of 4-5 days before wilting and a group of flowers last around 2 weeks- Styrax japonicus (Wikipedia)
Styrax japonicus (野茉莉, also エゴノキ, egonoki), also known as the Japanese snowbell, is a species of flowering plant in the family Styracaceae, native to Korea, Japan, and Southern China. Growing to 12 m (39 ft) tall by 8 m (26 ft) broad, it is a graceful, spreading deciduous tree with oval, upward-facing leaves which occasionally turn yellow or orange before falling in autumn. Masses of slightly fragrant, bell-shaped white flowers hang from the branches in summer, followed by fruits (drupes) which resemble olives in both shape and colour.