The title, translated from Japanese, is Great Detective Pikachu ~Birth of a new Combination~. It will be released on the Nintendo 3DS via eShop on February 3rd in Japan. The game will retail for ￥1,200 or $10 USD. Download requires 6,400 blocks or 800mb of free space.
Translated version of the trailer’s text:
In a city full of hidden riddles, a mysterious meeting. A new tale emerges.
(Pikachu) “I smell a new case” (to male protagonist) “Where do you think you’re going?” “Let’s look for answers!” “Are you alright?!” “Let’s go, partner!”
Their adventure is just beginning. The protagonist this time is (Great Detective Pikachu). Excellent, talkative, can’t-help-but-love-him Great Detective Pikachu. The Pikachu you’ve never seen before is here.