The nationals representative selection competition. Kazusa's family was attending it, including Nene. When Chika went to buy drinks for the guys after their show, he happened to meet Nene. They even exchanged gifts, Chika receiving an origami (I think) from Nene, and Nene receiving a strawberry drink from Chika. So, they are real close already, like best buddies. Chika wouldn't let go of anything strawberry if it was just a normal acquaintance.