Volume 1 contains the side story "Welcome Party!!"
Hokuto-sempai has been looking forward to time when he can get revenge for his own welcome party, so he arranges a traditional Welcome Party for Asahi-kun, but things don't go quite as he had dreamed it would.
Princess x Train
This is the second and final part of the series that begins with ]Train x Princess in Volume 3 of Princess Princess. Mikiyo Tsuda (Zaou) collaborated with Eiki Eiki to write this crossover story.