I swear this manga is getting lewder by the chapter. I wouldn't be surprised if they fuck by the time we reach chapter 50.
I'll mention once again, though, that the visuals in this series are extremely careful to avoid anything that looks ecchi at all---Hino's memory vision is of what's on Kugoma's panties, not of the panty-clad little bum itself.
The point being that the story is getting lewd (actually, it has been as lewd as this a number of times before), but the lewdness takes place in our heads, not on the page itself.
Number of direct references to Koguma's panties in the text: 12
Number of times readers have seen Koguma's panties: 0