But anyway, here's a rough comparison of events covered in both mediums (no spoilers)...
Note: the story is set in the '90s. According to the dates, it's apparently 1994.
E1 - ch00 (prologue)
E2 - ch1 (Yuuki Natsuno 01)
E3 - ch2 (Yuuki Natsuno 02)
-------volume 1 of manga
E4 - ch3 (Yuuki Natsuno 03)
E5 - ch4 (Yuuki Natsuno 04), ch5 (Masao extra 1)
-------volume 2 of manga. From here on, it gets a little confusing.
E6 - ch6 (Ozaki Toshio 01), most of ch7 (Yuuki Natsuno 05)
E7 - rest of ch7, half of ch8 (Yuuki Natsuno 06), ch12 (Masao extra 2)
E8 - rest of ch8, ch11 (Yuuki Natsuno 07)
E9 - ch9 (Ozaki Toshio 02), ch10 (Ozaki Toshio 03)
E10 - part of ch12, ch13 (Yuuki Natsuno 08)
--------volume 3/4 of manga
E11 - ch14-15 (Ozaki Toshio 04-05)
E12 - ch16-17 (Yuuki Natsuno 09-10)
--------volume 5 of manga
E13 - ch18 (Yuuki Natsuno 11), parts of ch19 (Ozaki Toshio 6), ch21 (Yuuki Natsuno 12)
Notes: Having only started looking at this recently (after episode 12, to be precise), I've had to rely on summaries, so it may need editing over the next few weeks. As I mentioned in a previous post, they may be aiming for a simultaneous anime/manga finish
---speculation for next episode...
E14 - ch20 (Ozaki Toshio: A certain doctor's record), rest of ch19, ch21(?)
--------volume 6 of manga
edit (2010-11-03): watched the preview for 14 a bit more carefully. We are definitely getting "A certain doctor's record" in the next episode...
final edit (2010-11-14): numbers changed to match the English releases
