I Can Hear My Childhood Friend's Thoughts?!

Saku and Azusa have been together. They were even born the same minute. Now that they're off to college, it's finally time for them to separate, and the ever-anxious Saku is feeling lonely while the calm and cool Azusa is as aloof as ever. One day, Saku suddenly hears Azusa in his head! What's more it almost sounds like Azusa is in the middle of...