Guren Shingeki

Guren Shingeki (紅蓮反撃, Crimson Lotus Counterattack) is Kyūbi Naruto's up special move in Super Smash Flash 2. Kyūbi Naruto jumps diagonally upwards while spinning, dealing multiple fire-based hits.

Origin
Because of the great heatred infused in the Chakra of the Tailed Beast inside Naruto, the Red Chakra Cloak that covers Naruto’s body tends to burn anything and anyone who touches it, even Naruto himself, while shortening his lifespan in the process.

As the series progress, Naruto has learned how to control the Chakra of his Tailed Beast, thus removing the hatred from it.

And when Naruto and his Tailed Beast, Kurama, finally found peace between each other, and Naruto gained full access to the complete unmeasurable power of his Tailed Beast, Kurama’s Chakra seems to have been fully released from its hatred, thus allowing contact from others without burning them.

If Naruto will gain full-control of his Tailed Beast's power on this game, or if it will remain on this level is unknown.

Trivia

 * Of all the techniques of  Kyūbi Naruto, this is the only one that wasn't inspired neither from the Manga nor the Anime. Rather, this attack comes from one of Pre-Timeskip Naruto's combo attacks in the Narutimate Accel series of video games.