Akuninzura shita B-kyuu Boukensha - Shujinkou to Sono Osananajimi-tachi no Papa ni naru

I only read the English version once or twice, but I've read the Japanese version... I dunno, but more than 30 times by now (It's my go-to braincandy). Note: I haven't read the Novel, so I can only give my point of view from the manga.

1. They don't directly call her mom-like, but they do insinuate that she is a motherly figure... which she is.
2. They never call her wife-like or whatever.
3. I don't think the ex-girlfriend saw her as a love-rival. She was more worried about who he had those kids with (including Ariameru).
4. I never read the brother suggesting that she is crushing on MC or that she was eavesdropping at all. Did you get this from the novel? I was convinced se was embarrassed the next day because she was seen with dishevelled morning hair.

I'll have to read the novel to make sure, but I really, really hope you're wrong. Developing love-interest for the child you're caring for messes up every manga. Thankfully, the mangas that do this are usually cancelled before it happens in the novel. I pray to the manga-gods that Emiria (Ex-girlfriend) will be the love interest or that he, at the very least, just stays a single dad. So far, this has been a great child-care manga. Usually, the child-care aspect is put to the side in favour of plot or romantic development, but this one consistently stays on track. It's not my favourite manga ever, but it's definitely the most re-readable for me. For the love of the manga-god, don't mess this up, I'm begging you

I reaaaallly want to like this, but they keep making weird comments about the 13 YEAR OLD ADOPTED DAUGHTER. The sus: “she looks like a mom more than a big sis” (1 count), “she looks like a wife” (1 count), ex-girlfriend thought she was a love rival on first meeting (1 count), brother suggested that she is crushing on MC after she eavesdropped on MC talking about ex-gf (1 count).

Don’t do this, mangaka-sama. Please don’t go down that road.

While there are some dark elements and themes in this manga, it does not distract the reader from the beautiful family created by the protagonist. It's totally different from the cringe I normally see in other isekai mangas where a man grooms girls as they get older. It's mainly a heartwarming story of orphans that got lucky to meet such a kind man (with a scary face.) The only downside is just the slow updates.

Gap moe main character that chops bad people's heads off and raises children. Not much else to say so far other than that as it's only been 4 chapters but it's a cute and fluffy manga with some decapitation on the side.