Mishiko

Diminutive of Misha and Misho, which are both diminutives of Mikheil.

In other words: this name is a double diminutive of Mikheil.

From Japanese 実 (mi) meaning "fruit, good result, truth" or 美 (mi) meaning "beautiful", 志 (shi) meaning "purpose, will, determination, aspiration, ambition", 司 (shi) meaning "director, official, govt office, rule, administer", 孜 (shi) meaning "industriousness", 枝 (shi) meaning "branch" or 詩 (shi) meaning "poem, poetry" combined with 子 (ko) meaning "child". Other kanji combinations are possible.