One of Wanikani’s greatest delights is the Tsurukame App. If you are a mobile heavy iOS user, I request you to try Tsurukame. David Sansome’s creation is a thing of beauty that stands at the delicate intersection of Art and Technology. I have completed half my levels (12) on a mobile browser and another half (12) on Tsurukame, the ease and improvement in quality of life is tremendous.
There is a Japanese story behind the origin of the word “Tsurukame”
Japanese of the ancient times believed that by uttering bad words they would bring about bad omens. But if the inevitable happened and the taboo words were to be pronounced, the repetition of the names of these two auspicious animals: tsurukame , tsurukame , tsurukame (crane-turtle, crane-turtle, crane-turtle) could ward off the evil.
And I know, I am uttering “Tsurukame” thrice when I make unintended errors in WK and correct my mistakes through Tsurukame App 
For enriching the lives of countless durtles, @davidsansome, I give you my heartfelt thanks and wish you the longevity of a Tsurukame. I bestow upon you the title of Tsurukame Durtle