In Japanese mahjong, Kokushi Musou is one of the biggest yakuman hands.
Tips
history
From 《史记·淮阴侯列传》: 诸将易得耳,至如信者,国士无双 — Xiao He telling Liu Bang that generals are easy to find, but a man like Han Xin is one-of-a-kind in the realm.
culture
In Japanese riichi mahjong the idiom names the 13-orphans yakuman (国士無双) — a hand of all 1s, 9s, and honor tiles. Chinese mahjong fans borrow the term back.