This volume of MPD psycho is my favorite volume thus far. I found it faster moving than Vol 2 and 3 and I found it up to par with and being as awesome as Vol 1.
The Plot on this one is as simple as it gets, Toguchi (the reporter with the eye patch) goes insane from a combination of remembering war time atricities that had occured as well as him feeling like he is not as famous as he should be and does not get the regcognition that he deserves as an artist. Toguchi grabs an assault rifle and goes on a rampage killing people on site. He meets a girl who is mercilessly bullied and recruits her to be his accomplice. He takes over the media station that he works for wanting to "change Japan", in the process he angers another killer, Zibatsu and than stuff really starts exploding!
This whole volume tends to deviate away from the main story arc of the series with slight mentions of Gasku in the beginning and at the end. The end is pehnominal and it shows the real power of Gasku and their ability to manipulate and act in plain sight with out anyone noticing.
Lastly the social implications are excellent. The plot makes notice of terrorism especialy in Japan with its constant mention of Ricin which was used in a Tokyo terror attack in the past. It seems as if Gasku is supposed to be a more powerful moderenized version of Shining Path, and the manga ultimately echos the fear of such a subversive orginization. Lastly I feel that much like GitS this manga is a commentary on the corrupt state of the Japanese police as well as a commentary on how Japan is ultimately becoming a police state.
I definately recommend this manga as it was interesting, action filled and fast paced. This volume had the most violence to date, but it was for the most part gun violence and lacked the sadistic quality of Vols 1-3. You will absolutely love this on, get it!
By the way, I noticed another review mentioned that the plot for this one was hard to follow, I have to say he is incorrect in my opinion as I found this volume the easiest to follow. I will agree with him that Vols 2-3 were much harder to follow, but this one was definately the most straight forward thus far.
Additionally, the other review complained that this manga is not "realistic". I'm not sure I have read any manga that has a realistic plot yet. Many of the greats are sci fi based, does one consider Evangelion realistic? or DBZ? or Berserk? Ultimately I think this one having relevance to terrorism and a deep rooted secret society that has penetrated society and the Japanese government is far more realistic than "Angels" coming from another planet and destroying a decoy version of Tokyo...