I can definitely see Mona becoming a huge Naoi/Kurumi shipper in the near future

I'm not sure if this is that type of manga

I have no idea where this Mona plotline could possibly go, but im here for it

See you all next month

Mona is trying to get Kurumi to like her in order to use her to manipulate Naoi, right? I don't think she has outright malice or even necessarily knows what she's doing so much as she lives in an emotionally unstable and manipulative environment, with the baby being used to paper over the issues in their mom and stepdad's relationship.

But her empty eyes in the last panel makes me feel like it could get nasty. Kurumi also seems more open to her than most other people due to the resemblance to Naoi, she's even been very slightly blushing (cute!), and she's emotionally vulnerable due to reaching out to her mom...

Crack theory: Mona isn't trying to get Naoi back because family, it's because the last time their mom tried to save a relationship by having a kid she was the result, and Naoi became the black sheep. So she instead fears that will happen to her... unless Naoi comes back to reprise that role, then she's safe.

I mean, I doubt it'll go that way, but the way this work is going that wouldn't be off-tone.

Mona is trying to get Kurumi to like her in order to use her to manipulate Naoi, right? I don't think she has outright malice or even necessarily knows what she's doing so much as she lives in an emotionally unstable and manipulative environment, with the baby being used to paper over the issues in their mom and stepdad's relationship.

But her empty eyes in the last panel makes me feel like it could get nasty. Kurumi also seems more open to her than most other people due to the resemblance to Naoi, she's even been very slightly blushing (cute!), and she's emotionally vulnerable due to reaching out to her mom...

Kurumi has seemed uncomfortable for most of Mona's visit. Mona wants them to keep secrets from Naoi, which Kurumi's questioning of showed sweat drops in the bubble meaning she didn't like the request. Then Mona starts doing a series of invasive questions that Kurumi questions Mona's intent of. And Kurumi had a WTF reaction when Mona started talking about becoming like Kurumi's little sister. This is basically the same kind of setup as chapter 7, down to the location. Where Kurumi is being pressured into accepting a request that she doesn't really want to.

Unless the author wants to just rehash past arcs, odds are it's there to show how Kurumi handles it better this time around. Also, Kurumi never spoke to her mom yet, only her grandmother, and it was due to Naoi's support that Kurumi thought of that she even found the courage to set up a meeting with her mom in the first place, so saying it's already make her emotionally vulnerable is quite a stretch, since nothing bad happened yet.

If anything, the part of Mona's plan based around hanging out at Kurumi's house is in immediate danger after Kurumi's phone call with her mom, since her mom coming back means Mona wouldn't be able to stay there while Kurumi's sorting things out with her mom. Considering this has so far been framed as an emotional growth arc for Kurumi and Naoi, them making the same old mistakes from past arcs is less likely to happen.

Crack theory: Mona isn't trying to get Naoi back because family, it's because the last time their mom tried to save a relationship by having a kid she was the result, and Naoi became the black sheep. So she instead fears that will happen to her... unless Naoi comes back to reprise that role, then she's safe.

I mean, I doubt it'll go that way, but the way this work is going that wouldn't be off-tone.

I think you nailed it