Quick answer
Yoshiko is a girl name.
Meaning and history
From Japanese 良 ( yoshi ) meaning "good, virtuous, respectable", 芳 ( yoshi ) meaning "fragrant, virtuous, beautiful" or 悦 ( yoshi ) meaning "joy, pleased" combined with 子 ( ko ) meaning "child". This name can be formed from other kanji combinations as well.
Notes and context
Usage: japanese | Japanese Hiragana: よしこ; Japanese Katakana: ヨシコ