"Line Scratcher" is motif "Katanuki".
"Katanuki" is a Japanese festival activity.
"Katanuki"s object is carve the outline which shape of a heart, star and rocket etc.
"Line Scratcher" can carve the line like a "Katanuki" and compete degree of accuracy of cutting shape.
If you come in Japan and like Japan culture, please play it.
you should improve skill of "Katanuki".