Under Ninja manga volume 6 features story and art by Kengo Hanazawa.

After Kurou thought he had begun to clean up Kodan High, the Under Ninja begin to make their move. And if you thought the government agents in this school were tough, the UN is a whole other story. They are well trained ninja with an agenda and access to modern weaponry. And they are ready to settle the score without any concern for collateral damage.