(historical) sangaku (ema on which is written an original maths (和算) problem and solution)

level of imports

calligraphy written on a frame and hung on a gate or palace

kowtow

(swords) an inscription where a blade is shortened and a rectangular metal piece bearing the original inscription is cut out from the removed portion and embedded in the new tang

(of bad thing) to increase rapidly or exponentially; to grow like rabbits breeding