真剣
1
serious;earnest
ジョージは勉強に真剣でない。
George is not serious about his study.
2
real sword (as opposed to a wooden practice weapon)
「親父これって・・・真剣？」「当たり前だろう、決闘なのだからな」
"Dad, this a real sword?" "Of course, it is a duel after all."