Kyou realizes on the fifth day, when Hiroko greets him on the way to school, that her acting more robot-like was going to cause problems because her parents have started to notice her behaving strangely, so he mentions wanting to tinker some more so she and the others don't get discovered. Ultimately in the (original) epilogue he ends up having them behave like their human selves for the most part, save for when he deliberately activates their robot modes and such.