Ch 166/167 Denji blames his dick for not being able to keep his priorities straight and his way of thinking. In Ch. 164, Asa tells Denji that she wants to help him because of his situation. Since Asa doesn't know what to do to help Denji during his mental breakdown, Yoru takes control of her and suggests to Denji for her to cut his dick off.

When they go to the alleyway, Denji seems to look around to see if anyone is nearby. When Asa (Yoru) actually states she’s going to cut his dick off, he was in disbelief and changed his mind after confirming she was serious about doing it.  

If you combine Ch. 167 cutting straight to the end of the alleyway, Denji looking around most likely for privacy before their interaction, and his reaction to what Asa (Yoru) said, we can infer that Denji thought she was going to sexually relieve him and probably thought “I’ll cut it off for you” as a figure of speech. Yoru’s purpose for her actions was to cheer up Denji so that he could become CSM and they could fight.  

That is until she remembers that they have kissed before. Her facial expression is that of Asa's, but Yoru is still in the driver’s seat. I view this as more so Asa’s reaction to the memories, but it wasn’t enough for her to switch control.

Once Yoru confirms by kissing Denji, Asa's feelings towards Denji flow into Yoru. This causes Yoru to feel an intense attraction towards Denji and makes her kiss him more intensely. In the following panels, we see after Denji processes her kissing; he kisses her back before nutting on her hand.  

Ch. 168 We see Denji sitting down on the ground, most likely to relax after being in a mildly intense, intimate situation with Asa (Yoru). We also know that Yoru likes to act on impulse, and she kisses Denji again because it feels good for her. After Yoru tells him she doesn’t like him, mentions “the other me likes you,” and then leaves, Denji is confused and trying to process what just happened.  

Asa did not deny about kissing Denji feeling good and was more worried about how Denji would perceive her because of how casually Yoru acted during the situation.  

Ch.169 Denji is still in a state of confusion because of his first experience of a "hand job." He is still currently dealing with Nayuta being MIA, along with his house being burned, etc. He notes that her “hand job” made his heart feel very nice. However, because of his current situation and him feeling good and being around food, he doesn’t know how he should feel in the present moment.  

Ch 181. Towards the end of the chapter, we see Yoru venting her frustration towards Denji for being in their predicament, and Denji responds by accepting the blame and views it as a punishment for being involved with people and a horny idiot. While he’s crying, we can see on Yoru’s face emotions of sympathy, remorse, and affection.

Wanting to comfort Denji, she kisses him in order to make him feel good because that is the best way she knows how to comfort him. Yoru is not great at empathy and emotions, for example in Ch. 164, when she told Denji that Nayuta was dead and to face reality. After realizing it didn’t work, she switched back to Asa.  

Things I noticed: -While Denji was crying, his mouth was partially open; however, when Yoru kissed him, his mouth was closed, and more tears ran down his face. His eyes seemed to be wide open and lifeless.  

-Asa's emotions have seemed to impact Yoru’s feelings towards Denji, and she is becoming more attracted to Denji. The conversation in the end of Ch. 181 happened with no switching or input with Asa. It seems there is less and less interaction between Asa and Denji.  

-The kiss on Ch. 181 reminds me of the prince kissing Aurora and the prince kissing Snow White photos; I wonder if there is an allegory to be made there.