novelty lover; fad chaser
Describes a person who is always attracted to new things or the latest trends, often with a slightly critical or teasing tone. The 屋 suffix marks a person with that trait.
He's a novelty lover and replaces his phone every time the latest model comes out.
うちの上司は新しがり屋だから、新しいプロジェクトが始まるとすぐに飛びつく。
Our boss is a fad chaser, so he jumps on any new project right away.