最盛 さいせい
saiseiki

Noun

1. golden age; prime; heyday; height of prosperity

その歌手 かしゅはあの きょく最盛 さいせい にあった。
sono kashuwa ano kyokude saisēkini atta.
The singer was at his best in that song.
Noun

2. season (for fruit, vegetables, etc.); best time

いまはカキの最盛 さいせい だ。
imawa kakino saisēkida.
Oysters are in season now.