Some claim that this name was given to the trains because of their appealing smallness, and others say it was because of their dark blue livery, similar in color to the Japanese cartoon character Little Ding-dong.
有人說因為它比西部的火車小了一截，看起來很可愛；也有人說是因為它的藍色車身很像日本漫畫裡的「機器貓小叮噹」。