Full title: Gintama: Gintama Quest ~Gin-san ga Tenshokushitari Sekai wo Sukuttari~
This colorful 2D RPG by Banpresto will be the second Gintama game on the DS. Looks quite charming.
http://bp-gintama.com/
http://www.famitsu.com/game/coming/1210573_1407.html
Comes out December 6th.