Using the same principle of Shuriken Shadow Clone, Koshiro creates a thousand shadow clones from one Flash Bomb, all exploding at once. This is a technique that combines ninja tools with ninjutsu. Compared to normal shadow clones, clones of material objects are said to be on a far higher level. There is no need for preparations beforehand, like stocking up on Flash Bombs, yet since the shadow clones are real and not illusions, the resulting Flash is just as lethal. Koshiro increases it's strength by using his Earth Release to create a dome of complete darkness. After using this jutsu, his enemies eyes are usually damaged greatly as their eyes are exposed to such a powerful light after being in the dark. However, this technique is a double edged sword as Koshiro must cover his eyes before activating it.
It's mostly used for his Chinsenka purposes as the bright light blinds the eyes, thus voided Dojutsu.