noun, noun which may take the genitive case particle 'no'
younger days; youth
A slightly literary or reflective term for one's younger days, often used in reminiscence. Can function as a noun or as a no-adjective modifying another noun.
My grandfather often talks about memories of his younger days.
I regret the mistakes of my youth.
Compound of 若き (classical attributive form of 若い, 'young') and 日 ('day'). The use of the classical adjective form gives the word a literary feel.