シャイ

しゃい
na-adjective
shy
informaldescriptive
1. shy, timid
Feeling nervous or uncomfortable around others, especially in unfamiliar social situations. A loanword used as a na-adjective.
He has a shy personality.
I'm too shy to start conversations myself.
It is said that many Japanese people are shy.

Etymology

From English "shy."

Similar words

Register

シャイ is used casually in conversation. In more formal writing, 内気(うちき) or 恥(は)ずかしがり屋(や) would be more natural.