noun
extreme mental weakness; fragile heart
Slang term likening one's mental resilience to the softness of tofu; used for someone who is easily hurt, discouraged, or emotionally fragile.
彼は豆腐メンタルだから、ちょっとした批判でもすぐ落ち込む。
He has a tofu-soft mental state, so even a little criticism gets him down right away.
そんな豆腐メンタルじゃ、社会人としてやっていけないよ。
With such a fragile heart, you won't make it as a working adult.