君子 in Chinese / Japanese...

This means nobleman, person of noble character, man of virtue; wise man, or a true gentleman

君子 can be romanized as chün-tzu or jūnzǐ from Chinese and gunja from Korean. This has the same meaning in Japanese, but in another context, can be the female given name Kunshi.

君子の拳 is “Kunshi no Ken” in Japanese.

The meaning is literally “Noble Fist” or “Fist of Nobility” but it's often used to describe the effort to concentrate on cultivating oneself to become a well-rounded, respectful individual.

You will see 君子の拳 sometimes written in the full Kanji form of 君子之拳. Both versions mean the same thing. If you want this more traditional Kanji version, just let me know when you place your order.

君子豹変す is a Japanese proverb that suggests that a wise man is willing to change his mind, but a fool will stubbornly never change his.

The first word is 君子 (kunshi), a man of virtue, a person of high rank, a wise man.

The second word is 豹変 (hyouhen), sudden change, complete change.

The last part, す (su), modifies the verb to a more humble form.

The “fool” part is merely implied or understood. So if wise and noble people are willing to change their minds, it automatically says that foolish people are unwilling to change.