Keigo was so sweet to Nanami upon arrival it was so nice ;-; she didn't have the smoothest of arrivals but Keigo was one of a lot of people who helped Nanami feel a bit more normal immediately. The kindness was deeply appreciated.

I'd imagine that at this point the two have spent some time making cute and (at least in Nanami's case) somewhat crudely drawn posters, which have gone all over the school by this point.

I DON'T KNOW I think they're really cute?? Keigo's somebody Nanami trusts, even if Nanami isn't gonna tell them much about her past life (too many triggers there), she is gonna seek Keigo out after classes to chat or hang out, and Nanami's gonna return the favor of helping her & bringing her to work on marketing posters by dragging Keigo to game club and/or nicking the school Game Boy Color for an afternoon to show Keigo vidya games.