As of April 5, 2006, a series known as Norisuta Haai began airing five minute Hamtaro episodes known as "Tottoko Hamutaro: Norisuta Haai!" The Norisuta Haai series is animated differently from the original series, most notably how the head-to-body ratio is off, and is designed to appeal to a younger audience. There does not seem to be any connection between Tottoko Hamutaro and Tottoko Hamutaro: Norisuta Haai beyond the planned appearance of all fifteen original Ham-Hams.
Norisuta Haai is itself a younger audience program. The particle "Haai" is some kind of salute in Japan, to say "good morning", mainly. In the program they're always saying "Haai", like Hamtaro and his "nanoda".
The DS game "Hamtaro: Ham-Ham Challenge" uses the designs from Hamutaro Haai, and, in Japanese, the game is called "Tottoko Hamtaro Haai! Hamu-Chans no Hamu Hamu Challenge! Atsumare Haai!" in allusion to that series.