“Heyday” in Japanese
Short answer
Heyday in Japanese is “全盛期” (zenseiki). Full meaning: heyday, golden age.
Other ways to say “Heyday” in Japanese
我が世の春
wagayonoharu heyday, prime, one's glory, the height of one's prosperity
最盛期
saiseiki golden age, prime, heyday, height of prosperity; season (for fruit, vegetables, etc.), best time
春
shun spring, springtime; New Year; prime (of life), height (of one's prosperity), heyday
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