expression, noun
thorn in one's side; pain in the neck; nuisance
Idiomatic expression referring to someone who is a constant source of irritation or obstacle, often a superior or someone more capable. Literally 'a bump above one's eye'.
彼は私にとって目の上のこぶのような存在だ。
He is like a thorn in my side.
あの先輩はまさに目の上のこぶで、いつも口出ししてくる。
That senior colleague is a real pain in the neck, always butting in.