Its other names are Suki na mono wa Dakara Shoganai! or Sukisyo! It ran from January 8, 2005 to March 26, 2005. It is a light novel that expanded to 5 games, 12 anime episodes and one OVA.
Plot: Sora Hashiba can't remember a bunch of things after falling out of the fourth floor window. An old childhood friend, Sunao, or Nao as he likes to be called appears, but he can't remember him. Masuri, Sora's doormate and childhood friend, keeps trying to get rich quick with his silly schemes. Both Nao and Sora have a dark past, during the past they had created alternate personalities that like to take control. Nao's alternate personality is named "Ran" and he is in a relationship with Sora's alternate personality. Sora doesn't know that after falling out of the window, which leads to awkward situations when one of them gets control back.
My rating: I would say even though its old, you should watch it. It looks light-hearted at first but there's this underlying tone of darkness that I find interesting. I love this anime to pieces and think everyone should give it a try.