He has a lot of nerve.
At that young age, he made a gutsy decision.
More common and colloquial form with the same meaning; 肝玉 is a rarer, slightly more literary variant.
Standard kanji spelling for this rare term.
Variant kanji spelling; less common than 肝玉.
Variant kanji spelling; less common than 肝玉.
Compound of 肝 (きも, 'liver') and 玉 (たま, 'ball, jewel'), metaphorically referring to the seat of courage. The exact historical derivation is uncertain.