The ‘Letterform-Play’ series is a work about puns on words played by comedians and children. Using onomatopoeia, imitative words, or transliterations of foreign languages, he deconstructs the meaning of a language or draws sounds or notations of the character itself. Woo soo soo soo means tears or leaves fall one after another, and in the case of Woo soo soo soo, he visualized the image of the letterform falling.