overqualified person; educational refugee
A person whose high educational background makes it difficult to find a job matching their qualifications, often leading to underemployment. The term carries a critical or sympathetic tone about the mismatch between education and the labor market.
Even though he has a PhD, he ended up as an overqualified person unable to find a suitable job.
The number of educational refugees is increasing due to the recession.
Compound of 学歴 (academic background) and 難民 (refugee), literally 'educational refugee'. The term likely emerged in the context of Japan's employment struggles for highly educated individuals.