In Chapter 18, it looks like he finally recognizes Miya.
That's what I saw in Chapter 18.1. I hope they don't drag it out any longer, and then say she's just a distant relative or something.
Chapter 18.1 ends with the protagonist calling her Miya.
Her sister wasn’t born when he left and she calls Miya nee-chan or something of the like. So unless she’s the spitting image of Miya’s younger self, there’s no reason his braindead oyster would connect the dots. On the other hand, meeting her mom would be a dead give-away.