一騎当千
i-.kki.tou.sen

Literally: one – equestrian – hit – thousand

Alternately: Mighty. So strong that a thousand opponents still cannot match them.

Notes: This can be expanded to the descriptive noun phrase 一騎当千の兵 (ikkitousen no tsuwamono), “a warrior who can defeat a thousand.” This is actually a pretty old one but native to Japan, first attested in the 14th-century epic Taiheiki.

Also the name of a manga and anime series! “Based on” the Romance of the Three Kingdoms! Actually about nearly-naked schoolgirls (and less-naked guys) beating each other up! You would not believe how long it took to find an image clean enough to illustrate it with! Source!