On Christmas Eve the gang runs into Azuma-sensei and his childhood friend, Akira. While trying to help a little girl Chizuru accidentally knocks over a Christmas tree forcing all of them to dress up and work with Akira as Santa Claus.

Shun worries about how fast his little brother's relationship is progressing - he thinks kissing is too early for middle schoolers. He calls over the gang to discuss the "emergency" which only worsens his anxieties. As a result the gang spies on his hormonal brother's date, and hilarity ensues.