As Mayuri Shiina prepares for a Christmas party for everyone at the lab, Rintaro shows Amadeus Kurisu – whom he keeps a secret from his friends – around Akihabara and the lab. On Christmas Eve, Leskinen and Maho end up joining Rintaro at the party, which proves to be more than a surprise when Suzuha assumes it is an ambush and almost attacks Yuki...