I assume Chizuru told Umi when asked about how she feels about Kazuya that "I don't not like him" and so Umi, deciding to play the matchmaker between these clearly two people who're into each other, decided to slip that question to Kazuya and see how he responds to it. Given the response he got, Umi confirmed that both sides mutually like each other.
Although if that's the case, are we going to have another shipper on deck aside from Yaemori?