Fool

Fool  (だます, Damasu) is the 9th chapter of Volume three and the twenty-fifth chapter of the Death Note manga series.

Plot
Light Yagami has been watching the broadcast of the latest Kira tape on TV and is amused. He had nothing to do with the tapes but it is clear that there is someone out there who has a second Death Note and has traded half of his life for the Shinigami Eyes, the only way he could have killed passing policemen without knowing their names.

Light himself does not want to trade half his life for the Shinigami Eyes but since this new Kira has already done so then he could kill L if he sees him on TV. He could also be used in order to clear Light of any suspicion of being Kira. On the other hand, the killing of broadcasters and policemen could cost Kira valuable public support.

Light decides to join the Kira Task Force in order to keep an eye on both L and the fake Kira. If the fake Kira messes up, Light should be able to catch and kill him before L and get his Death Note.

Two days later, Soichiro Yagami arrives at the Kira Task Force's hotel room after attending an important meeting with representatives of Interpol. The pressure is on for L to appear on TV without deception. L understands their frustration, given the fact that Kira has threatened to kill other policemen instead. On the other hand, the real question is how to convince Kira that he, L, is the genuine article. Furthermore, L tells his fellow detectives that he also believes that there is a strong chance that this is the work of a Second Kira!

The officers are bewildered, but L explains his reasoning. The Kira he imagines would have made better quality tapes than the ones that they received. What's more, in order to prove his genuineness, the Second Kira killed two minor crooks who had barely been mentioned in the media, while the real Kira usually goes after hard-core criminals. The Second Kira also killed two critical newscasters live on TV, while the original Kira has never bothered with his critics before. There is also the killing of the police officers who tried to stop the broadcast. The reckless actions of the Second Kira amount to terrorism to force his will onto the public, while the original Kira proceeded more prudently and cautiously, letting the public slowly adopt his point of view.

Coming round to his way of thinking, Aizawa and Matsuda also point out that it is unlikely that Kira would have left behind the fingerprints found on the tapes and envelope, which leads L to assume that the Second Kira is of a lower intellectual level than the real one. He also notes how the fingerprints are small, probably those of a child or a woman.

He now believes that they are in a race to find the Second Kira before the real Kira does and there is a good chance that one might lead to the other. Kira may also want to use the Second Kira and dispose of him when he no longer needs him.

L asks Soichiro to invite Light to work with them in catching the Second Kira. He admits that Light is not clear of suspicion of being Kira but his profiling skills are very promising. However, he does not want Light to be told there is a chance of there being a Second Kira.

Meanwhile, in the streets of Tokyo, a young blond girl named Misa Amane walks around with her Shinigami Rem. Rem warns Misa of what she is getting into by trying to contact Kira, but Misa is determined to meet him and her special Eyes will be an asset if things get nasty.

Conception
When Ohba was discussing the title for the chapter "Fool," he said "Death Note finally gets a heroine in this chapter and she's called a "fool"... How rude. But that's just Death Note for you."