Denshi Jisho — Online Japanese dictionary

幼い おさない 1: very young;
2: childish; immature
Common word, Adjective 
幼い いとけない 1: very young;
2: childish; immature
Adjective 
幼い頃 おさないころ as a child; when one was a child
Expression 
幼いころ おさないころ as a child; when one was a child
Expression 

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