noun
idealist
Refers to a person who pursues or believes in ideals, often with a nuance of being somewhat impractical or visionary.
彼は理想家で、現実的な問題にはあまり関心がない。
He is an idealist and isn't very interested in practical problems.
Compound of 理想 (ideal) and 家 (person who does or specializes in something).