A post clear side story is included in Gintama Rumble

The latest issue of V-Jump reveals that Gintama Rumble unlocks a side story once you clear all the chapters of the story mode. It is also explained that playable characters can be set as assist characters. You will find assist characters like Housen, Okada, Doromizu, Saigou, Abuto, Utsuro, Oboro, Sasaki, Ayame, Tama, Tae, Date Umibouzu, Bansai, Matako, Elizabeth, Sadaharu, Kyuubei, Taizou, or Neo Armstrong Cyclone Jet Armstrong Cannon. The game will launch in Japan on PS4 and PS Vita on January 18 next year, as well as in Southeast Asia with English subtitles.