No exact date yet but the sequel will feature 5 cases and 30 mini quests to go through. Entitled "Osawari Tantei Kozawa Risa Season 2 1/2: Risa saw it! No, Risa didn't!" the first case involves tracking down whoever stole the colours from coloured Soumen (noodles)...

Also in commemoration of this sequel, a fan club "Osawari Tantei-dan" is being setup for accepting any fanart players would like to submit.

Source:
• Dengeki

Related Links:
• Official Site