Chainsaw Man currently has many questions at the moment regarding how the story could end, but right now the most prevalent question is concerning Yoru's intentions. The recently published chapter 195 had Asa Mitaka tell Denji that the War Devil wants to do something so evil that she can't even say it, which most people relate to the Death Devil but could be entirely different.
The general perception among the Chainsaw Man community is that Yoru's main target is to destroy the Death Devil so there can be endless war, but the reality could have changed a bit now. Yoru's intentions could be connected to Denji, wanting to bond with him on a more intimate level, which Asa could be against.
Disclaimer: This article contains spoilers for the series. This article is speculative and any opinion expressed here belongs to the author.
Explaining how Yoru's plans in Chainsaw Man might not be what she claims to be

It was established earlier during Yoru's introduction as the War Devil that she wanted to recover the Nuclear Devil so she could cause warfare so people could fear her and make her stronger. However, as the character evolves throughout the series, she becomes much more intimate with Denji, and there is an argument that she wants to be in bed with the protagonist, much to Asa Mitaka's rejection.
Most people have assumed that Yoru's true goal has to be extremely horrible, considering Asa doesn't want to say it, but she has witnessed enough awful acts to have the courage to tell Denji the truth. Furthermore, even though she couldn't say it because it is a concept that Pochita erased, Asa should be aware of it because of her connection with the War Devil.
There is a good chance that this could be connected to a potential intimate encounter between Denji and Yoru, and Asa doesn't want to say it because she thinks the protagonist would still want to follow through with that. It fits with Asa's personality and also with recent events where Yoru has gotten closer to Denji without the former's consent.
Asta might not trust Denji to tell him the entirety of the truth

It is also worth pointing out that Chainsaw Man could provide a twist by Yoru having two different goals, one being the aforementioned one and the other being Denji killing the Death Devil. This would make sense as she could be with him, which she wants, and become stronger since she wouldn't die and war could be endless.
Therefore, she could keep up her position of power since she would be able to dominate Denji and Pochita in battle while also keeping the protagonist by her side. It would explain Asa not wanting to tell him about it because she doesn't know him very well and doesn't know how he would react in that scenario.
Final thoughts
There is a good chance that Chainsaw Man could be preparing a twist with Yoru's character and what her true intentions are in the story. Moreover, her recent attraction toward Denji could also make this theory somewhat logical, especially considering how Asa feels in this situation.
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