First of all very nice job. I liked how the passage of time was done with Oomori going from going to "person you met at a park bench" to "person you visit a love hotel with". The sex scene was also well done.
Second, and other people have pointed this out also, this reads like it was made by Shaft. I didn't think it could ever work for manga because of all their crazy visual effects but it actually works well.
Definitely looking forward to more.