undulating gable; cusped gable; karahafu
A traditional Japanese architectural feature: a gable with a distinctive bow-shaped curve at the top, often seen on temples, castles, and gates.
二条城の唐門には立派な唐破風が付いている。
The Karamon gate at Nijō Castle has a magnificent undulating gable.
神社の本殿の屋根に唐破風が見られる。
You can see a cusped gable on the roof of the shrine's main hall.
千鳥破風 is a triangular dormer gable, while 唐破風 has a curved, wave-like top.
Formed from 唐, here marking an ornate or exotic style, and 破風, “gable.” The architectural form developed in Japan, though its name evokes continental styling.