In the year 2010, on a day called ‘Careless Monday', ten missiles hit the cities of Japan; miraculously, there are no casualties and the event quickly fades from public memory. Some time later, Saki Morimi decides to visit Washington, DC on her graduation trip to America, but that day begins a series of bizarre events. After getting into trouble with the police, she's rescued by a young man who is completely naked save for a gun in one hand and an even stranger item in the other - a phone credited with 8 billion electronic yen and a female voice on the other end called Juiz who will fulfill his every wish. Having no recollection of his past and calling himself ‘Akira Takizawa', the young man accompanies Saki back to Japan in the hopes of discovering who he is. Akira's enigma quickly proves fascinating and Saki decides to help him rather than reunite with her family; but what neither realizes is that Akira is embroiled in a dark game of life and death linked to the Careless Monday missiles. Has Saki just made a terrible mistake, and can Akira unravel his own mystery before they both lose everything?
Cell phones and a mysterious orginization; if you liked this short animation then you'll like Eden of the East which extends the visuals and plot elements of this short.
Given they have the same director, same character designs and both are based around the concept of an ultra smart phone, these two anime are extremely recommended for each other.
Both revolve around super phones and a mystery. Eden gives the viewer more depth than Xi Avant does since it's only 4 minutes long but you'll appreciate one if you enjoyed the other.