Overview:Within the shadows of Japan, a covert battle wages on. Around 200,000 ninjas still exist carrying out deadly missions as a secret organization, National Intelligence of NINJA, or NIN. But a challenger arises: UNDER NINJA. Known as UN, these ninjas oppose NIN at every turn. One such UN is Kuro, a high school loner sent to the front lines. What will be his fate and which faction will prevail?