2 things that could be important to some people reading this.
There's a webnovel, and according to novelupdates translation is up to parution (145 chaps for now, it's ongoing).
It's not mentioned on mangadex, but it's harem. Yes, the characters are about 6 years old (for the girls) while mc is about 20 mental age)
Series that begins with toddler mc:
expectation: ah they'll grow up during essentially prologue and we'll follow their teen and early adulthood adventurers
reality: 1 day of in-series time per chapter at most.
Also the adultminded protagonists start to annoy me, especially if their childhood arc is overly long. Very rarely do they develop as characters while growing up, so why even bother? Besides, you are running adult.os, but you have child wetfare. That brain ain't developed and it should show up.
But nah, baby protagonist, but adult stories.