The protagonist of the story, Naoya, was hospitalised after getting in a bicycle accident. During his treatment, it is found that he exhibits a number of unusual brain wave patterns, and he is asked to move into a particular Cognition Dynamics Research Laboratory to undergo further testing, along with a handful of other young people who exhibit similar characteristics. With his newfound friends, Naoya takes classes, has fun and lives peacefully in blissful ignorance of the truth behind their gathering together.
While it is difficult to say much about the story without spoiling a good deal of the enjoyment, 'sense off' is not a title to underestimate, and in whichever route you end up going down, the story will quickly spiral into something far more intricate and detailed than you likely thought possible.

[Taken from a review by Asceai]