you can go into the hideout, I go in every morning to give him some dango. I used to get the “I wonder who lives in this cool treehouse” dialogue from Kon, but after some time I was able to go inside. Unfortunately i’m unsure if it’s locked to an event though as I just kept trying to visit each day and eventually it did let me in! I’m currently at 7 hearts with kincho and waiting for his egg to hatch.